Lesson Note on Chemistry SS1 First Term

Chemistry Lesson Note for SS1 First Term – Edudelight.com

SCHEME OF WORK CHEMISTRY SS1 

WEEKS         TOPICS

  1.             INTRODUCTION TO CHEMISTRY
  2.             LABORATORY FAMILIARIZATION
  3.             NATURE OF MATTER
  4.             ELEMENTS & SYMBOLS, VALENCY
  5.             COMPOUNDS AND MIXTURES
  6.             STANDARD SEPARATION TECHNIQUES FOR MIXTURES
  7.             PARTICULATE NATURE OF MATTER
  8.             IUPAC NOMENCLATURE OF CHEMICAL COMPOUNDS
  9.             ATOMIC NUMBER, MASS NUMBER, ISOTOPES AND CALCULATIONS
  10.             STRUCTURE OF THE ATOM: ORBITALS AND ELECTRONIC STRUCTURE OF THE ATOM
  11. REVISION
  12. EXAMINATION

REFERENCE MATERIALS

  • New School Chemistry for Senior Secondary School by Osei Yaw A.
  • Practical Chemistry for Schools and Colleges by G. O. Ojokuku
  • Calculation in Chemistry by E.U. Akusoba and G.O Ewelukwa
  • WASSCE Past Questions and Answers on Chemistry
  • UTME Past Questions and Answers on Chemistry

WEEK ONE

TOPIC: INTRODUCTION TO CHEMISTRY

CONTENT

  • CHEMISTRY AS A SCIENCE SUBJECT
  • BRANCHES OF CHEMISTRY
  • SOME LABORATORY APPARATUSES AND THEIR USES

CHEMISTRY AS A SCIENCE SUBJECT

Science is an organized body of knowledge gathered through systematic experimentations and philosophical observations. Chemistry can be defined as a branch of science which deals with the study of the nature, structure, composition, properties and uses of all forms of matter and the changes in structure and composition which matter undergoes.

BRANCHES OF CHEMISTRY

Chemistry is divided into three main branches, namely

Physical chemistry

Organic chemistry

Inorganic chemistry

Physical chemistry deals with the physical aspect of chemistry like quantum theory, heat and electricity.

Organic chemistry deals with the study of carbon and its compounds.

Inorganic chemistry deals with the study of elements, their properties and uses

SCIENTIFIC METHODS OF DISCOVERIES

Scientific method of discovery includes the following steps and stages:

  1. Observation
  2.  Pattern
  3. Problem
  4. Hypothesis,
  5. Experiments
  6. Theory
  7. Law

Hypothesis refers to a prediction or guesses which explains an observed problem. When the hypothesis has been tested and found to be true within the limits of available evidence, it becomes a theory. A theory which has been extensively tested and proven correct without any exception becomes a scientific law.

EVALUATION

  1. Define chemistry
  2. State the stages or steps involved in scientific discoveries
  3. When does a theory become a scientific law?

APPLICATIONS OF CHEMISTRY

Chemistry is applied in our everyday life as different activities take place in the environment. The effect of chemistry is felt in different aspects of life such as cooking, washing with soaps or detergent, digestion of food, drugs etc. Other applications of chemistry include health care, transportation, food, houses and clothes.

CAREER PROSPECTS IN CHEMISTRY

Chemistry is involved in our everyday lives and there is a vast range of careers open to those who have studied chemistry at any level. Great career opportunities exist both inside and outside the laboratory. You can choose a career from different fields such as:

  1. Pharmaceutical/drug development
  2. Science education
  3. Chemical engineering
  4. Mining and Metallurgy
  5. Pure and applied chemistry
  6. Petroleum and Petrochemical Engineering
  7. Quality control
  8. Medicine and surgery
  9. Chemical analysis/forensic science
  10. Environmental Chemistry
  11. Science Laboratory Technology
  12. Biochemistry etc  

EVALUATION

  1. State five applications of chemistry in our daily life.
    1. Mention five adverse effects of chemicals and how they can be controlled.

GENERAL EVALUATION

  1. Mention ten (10) career opportunities in chemistry.
    1. List the branches of chemistry.

READING ASSIGNMENT

  • New School Chemistry for SSS by O.Y Ababio. Pg 2 to 7
  • Practical Chemistry for School and Collegs by G. O. Ojokuku pg 2-15

WEEKEND ASSIGNMENT

  1. The aspect of chemistry that deals with the study of carbon and its compound is called (a) physical chemistry (b) Organic chemistry (c) Inorganic chemistry (d) Analytical chemistry
  2. Which of the following is not an adverse effect of chemistry? (a) pollution (b) poisoning (c) emulsion (d) corrosion
  3. A stage in scientific method of discoveries is (a) Evaporating (b) Hypothesis (c) Dehydrating (d) dissolving
  4. A theory which has been extensively tested and proven correct without any exception becomes (a) scientific law (b) hypothesis (c) experiment (d) pattern
  5. Career prospects in chemistry includes all the following EXCEPT (a) Biochemistry (b) Quality control (c) Accounting (d) Metallurgy

THEORY

  1. State five applications of chemistry in our daily life
  2. Mention five laboratory apparatus and their uses

Chemistry Lesson Note for SS1 First Term – Edudelight.com

WEEK TWO

TOPIC: LABORATORY FAMILIARIZATION

CONTENT

  • DEFINITION OF LABORATORY
  • LABORATORY APPARATUS; MEANING, USES AND IDENTIFICATION
  • LABORATORY SAFETY RULES


DEFINITION OF LABORATORY

A laboratory is a room or building equipped for scientific experimentation or research. It is a special facility where experiments are done and typically contains scientific equipment and apparatus.

LABORATORY APPARATUS

Laboratory apparatus refers to the various tools or equipment used by scientists working in the laboratory.

Some common laboratory apparatuses include: test tube, beaker, conical flask, flat bottomed flask, round-bottomed flask, funnel (plastic or glass) thistle funnel, brush, Woulff’s bottle tripod stand, retort stand, spatula, Bunsen burner, separating funnel, wire gauze, clamp, beehive shelf, gas jar, desiccated, reflux-condenser, Liebig condenser, pipette, burette, delivery tube, deflagrating spoon, u-tube, thermometer, aspirator bottle, wash bottle, chemical balance, reagent bottle, fume cupboard etc.

SOME LABORATORY APPARATUS AND THEIR USES

  1. EVAPORATING DISH:

It is made of porcelain. It may be round or flat bottomed. It is used in the evaporation of solution to dryness

  • BEAKER: It is available in different sizes. It is flat bottom cylindrical, graduated and usually with a lip for easy pouring of solution. It is used to hold solution or measure solution during an experiment.
  • ASPIRATOR BOTTLE:  It is a Jerry can made of plastic or glass with a screw tap. It is used for storing distilled water during an experiment.
  • CRUCIBLE: It is usually made of porcelain with a lid to match. It can withstand high temperature hence, it is used for ignition of substances until they are decomposed.
  • WOULFF’S BOTTLE: It is a glass bottle used during the preparation of dry gases to hold liquid or solutions that are employed as drying agents or in absorbing unwanted gases.
  • CONICAL FLASK: It is commonly used during titration experiments. It is usually graduated and used to estimate the volume of a solution.
  • FLAT AND ROUND BOTTOM FLASKS: They are made of glass and are mainly used for boiling especially during distillation experiments.
  • STANDARD VOLUMETRIC FLASK:  It has a flat-bottom, pear-shaped and with a narrow neck. It is used in preparing standard solutions to a specific or definite volume.
  • FUME CUPBOARD: It is usually a wooden cupboard with its front made of glass which can easily move up and down. It is used to prepare poisonous gases
  • DISTILLATION FLASK: It has a flat or round bottom with a slanting long side arm. It is used during distillation.
  • BELL JAR: It is made of thick glass, cylindrical, tall and usually with a knob at the top. It is used in combustion experiments.
  • GAS JAR:  It is made of thick glass, cylindrical, tall and sealed at the bottom. It is used for the collection of gas over water or dry gas
  • DROPPING BOTTLE OR DROPPING PIPETTE: It is used in keeping or transferring solutions or reagents that are required in drops during experiments.
  • SPATULA: It is made of iron which looks like a spoon. It is used in transferring little quantity of solids into test tubes
  • BURETTE: It is used during titration experiments and also in transferring small volume of solution.
  • RETORT STAND WITH CLAMP: It is used as support during experiments
  • DESSICATOR: It is used in keeping and drying solids in an atmosphere that is dry and free of dust.
  • MEASURING CYLINDER: It is used to measure the volume of solutions.
  • KIPPS APPARATUS: It is used in the intermittent supply of gases.
  • WIRE GUAZE: It is used as a support for flasks during heating.
  • FILTER FUNNEL: It is used in filling the burette or in supporting the filter paper during filtration.
  • CONDENSER (LIEBIG): It is used in cooling or condensing vapour into liquid during distillation or when refluxing.
  • CENTRIFUGE: It is used in separating fine solid particles in a liquid.
  • TEST-TUBE: It is used in qualitative analyses to hold reactants’
  • SEPARATING FUNNEL: It is used in the separation of immiscible liquids.

EVALUATION

  1. Mention ten (10) laboratory pieces of apparatus you know and their uses
  2. Define (a) Laboratory (b) Laboratory apparatus

IDENTIFICATION OF SOME LABORATORY APPARATUS

c  

Identify the laboratory apparatuses and laboratory set-up labeled A-I below:

B  
A  
I  
G  
H  
F  
E  
D  

LABORATORY SAFETY RULES

  1. Dress well for the laboratory: Wear lab coat, safety goggles, footwear and tie long hair back to avoid catching fire
  2. Keep pathways clear by placing items such as books and bags on the shelves or under the work table.
  3. Do not taste or smell chemicals
  4. Unauthorized experiments or procedures must not be attempted
  5. Pay close attention to any cautions described in the laboratory exercise
  6. Do not leave your assigned laboratory station without the permission of the teacher
  7. Do not lean, hang over or sit on the laboratory tables
  8. Fooling around or “horse play” in the laboratory is absolutely forbidden
  9. Learn location of the fire extinguisher, eye wash station, first aid kit and safety shower.
  10. Reports all accidents, injuries, and breakage of glass or equipment to instructor only.
  11. Always follow the instructions given by your teachers
  12. No eating or drinking in the laboratory at any time!
  13. Leave your work station clean and in good order before leaving the laboratory

GENERAL EVALUATION

  1. List ten safety measures in the laboratory
  2. State the uses of: (a) Evaporating dish (b) Pipette (c) Retort stand (d) Measuring cylinder (e) Conical flask

READING ASSIGNMENT

  • Practical Chemistry for School and Collegs by G. O. Ojokuku pg 2-15

WEEKEND ASSIGNMENT

  1. An apparatus in the laboratory in which the preparation of poisonous gases is done is called (a) distillation tank (b) Aspirator bottle (c) fume cupboard (d) bell jar
  2. In the laboratory _______ is used for the collection of a gas over water (a) gas jar (b) Woulff’s    bottle (c) reagent bottle (d)burette
  3. Two liquids which are immiscible with each other can be separated using (a) bell jar (b) gas jar (c) wash bottle (d) separating funnel
  4. An apparatus used to hold drying agents during the preparation of dry gases is (a) conical flask (b) gas jar (c) Woulff’s bottle (d) flat bottom flask
  5. Coloured reagent bottles are used to store reagents which are capable of _____ easily by sunlight  (a) evaporating (b) decomposing (c) dehydrating (d) dissolving

THEORY

  1. a.         Define Laboratory

b.         List five safety measures that must be taken when in the laboratory

  • State the use of the following apparatuses
  • Separating funnel
  • Condenser

Chemistry Lesson Note for SS1 First Term – Edudelight.com

WEEK THREE

TOPIC: NATURE OF MATTER

CONTENT

  • NATURE OF MATTER
  • COMPARISON BETWEEN SOLID, LIQUID AND GAS
  • TYPES OF CHANGE

NATURE OF MATTER

Matter is anything that has weight and occupies space. It exists in three states namely: solid, liquid and gas.

The fundamental difference between the three states of matter depends on the degree of movement of the particles they are made of.

SOLID STATE

The particles of a solid are tightly packed and held together by a strong electrostatic force.

The particles only vibrate to and fro about an equilibrium or a fixed position. They have a definite shape and volume and very difficult to compress.

LIQUID STATE

The forces of attraction between molecules of liquids are weak compared to that of solids. Hence they have slight movements. This is why liquids can flow. They have definite volume but not definite shape.

GASEOUS STATE

As a result of the distance between the molecules of gases, the cohesive forces between them are very negligible and so they move randomly. Gases have no definite shape and volume. They assume the shape of the containing vessel.

EVALUATION

  1. What is matter?
  2. List and explain the three states of matter.

COMPARISON BETWEEN SOLID, LIQUID AND GAS

SOLID                              LIQUID                               GAS

1.         Fixed mass                   Fixed mass                               Fixed mass

2.         Very dense                   Less dense                               Least dense

3.         Definite shape            Shapeless                                  Shapeless

4.         Definite volume            Definite volume                        No volume

5.         Incompressible             Incompressible                       Compressible

6.         Particles vibrate            Particles vibrate,                       Particles move

            and move about           rotate and move                       about constantly

            a fixed position           about a restricted space            at a fixed speed.

EVALUATION

  1. Define matter
  2. Compare the three states of matter in terms of (a) density (b) compressibility

TYPES OF CHANGES                   

Whenever a given substance is heated, its state changes. There are two types of changes: physical and chemical.

PHYSICAL CHANGE:

A physical change is a change which is easily reversible and in which no new substances are formed. Examples are:

  1. Dissolution of common salt
  2. Changes in states of matter such as melting of solids, freezing of liquids, evaporation of liquids, liquefaction of gases to solids, sublimation of solids.
  3. Magnetization and demagnetization of iron nails.
  4. Separation of mixture by evaporation, distillation, fractional distillation etc.

EVALUATION

  1. What is a physical change?
  2. Give two examples of a physical change.

CHEMICAL CHANGE:

A chemical change is a change which is not easily reversible and in which new substances are formed.

Examples of chemical change

  1. Rusting of iron/metals.
  2. Dissolution of metals and limestone in acids.
  3. Fermentation and decay of substances.
  4. Changes in electrochemical cells.
  5. The addition of water to quick lime.
  6. Burning of materials.

COMPARISON BETWEEN PHYSICAL AND CHEMICAL CHANGES

            Physical Change                                Chemical Change

1.         Easy to reverse                                     Difficult to reverse

2.         No new substances are                        New substances are always

            formed                                                 formed

3.         Very little energy changes                    There are often large heat

            take place                                             change.

4.         No change in mass                               The new substances formed have

different masses but the total mass is unchanged.

GENERAL EVALUATION/REVISION

  1. What is a chemical change?
  2. Give two examples of a chemical change.
  3. State three differences between physical and chemical changes.
  4. State the function of the following laboratory apparatuses: a) Fume cupboard b) Burette(c) Bunsen burner

READING ASSIGNMENT

  • New School Chemistry for SSS by O.Y. Ababio.Pg 8 -9

WEEKEND ASSIGNMENT

  1. Which of the following changes is a chemical change? (a) melting of ice (b) liquefaction of air (c) slaking of lime (d) evaporation of a liquid
  2. Which of the following substances will occupy a wider space? (a)carbon (iv) oxide (b) liquid milk (c) pieces of chalk (d) water
  3. When a solid changes to gas directly, this process is called (a) freezing (b) sublimation

            (c) vaporization (d) evaporation

  • Which of the following changes produces a new substance ?(a) reaction of water with sodium chloride (b) addition of acid to base (c) turning of margarine to oil (d) evaporation of water
  • Which one of the following has a fixed shape and volume?  

            (a) a cube of sugar (b) liquid wax (c) smoke  (d) kerosene

THEORY

  1. Give two differences between physical and chemical changes.
  2. Give three processes, which involve a physical change

WEEK FOUR

TOPIC:  ELEMENTS, SYMBOLS & VALENCY

CONTENT

  • ELEMENTS AND SYMBOLS
  • CLASSIFICATION OF ELEMENTS
  • VALENCY

ELEMENTS AND SYMBOLS

An element is a substance which cannot be split into simpler units by ordinary chemical process. There are over one hundred known elements.

SYMBOLS OF ELEMENTS

There are three ways in which symbols of elements are derived.

  1. From the first letter of the name of the element

Element                        Symbols

Hydrogen H

Oxygen                       O

Iodine                              I

Fluorine                              F

Nitrogen                              N

Sulphur                       S

Carbon                                 C

Phosphorus                         P

  • The first letter written in capital letter and one other letter from its name written in small letter.

Element                                    Symbol

Chlorine Cl

Bramine                                    Br

Calcium                                    Ca

Aluminium                                Al

Magnesium                               Mg

Berylium                                   Be

Helium                                      He

Neon                                        Ne

Lithium                         L

  • The symbols of some elements were derived from their Latin names.

Elements          Latin name                   Symbols

Mercury Hydragyrium Hg

Sodium            Natrium                        Na

Iron                  Ferrum                         Fe

Copper             Cuprum                        Cu

Silver                Argentum                     Ag

Tin                   Stannum                      Sn

Gold                 Aurum                          Au

Potassium        Kalium                          K

Lead                 Plumbum                     Pb

EVALUATION

  1.  How many elements are discovered now?
  2. Write the symbols for the following elements: silicon, iodine, fluorine, sulphur, silver, Iron, copper, potassium and sodium.

CLASSIFICATION OF ELEMENTS

Elements can be classified into metals and non-metals.

Examples of metals include iron, zinc, tin, aluminium, copper etc.

Examples of non-metals are: Chlorine, oxygen, sulphur, fluorine, hydrogen etc.

Some elements however possess the properties of metals as well as non-metals. They are called metalloids, examples are silicon and germanium.

THE DIFFERENCES BETWEEN METALS AND NON-METALS

Metal                                                    Non – metals

  1. They are solids (except mercury) They are solids, liquids and gases

2.         Good conductors of heat             Poor conductors of heat and electricity

and electricity                               (except graphite which conduct electricity)

3.         Malleable                                         Brittle

4.         Ductile                                      Not ductile

5.         Shiny                                                 Not shiny

  • Often very dense                                 Usually less dense(low density)

(high density) 

EVALUATION

  1. What are metalloids?
  2. State two differences between metals and non-metals.

VALENCY

Valency is the combining power of an element. It can also be defined as the number of hydrogen atoms that can combine with or replace one atom of that element.

Valency of an element depends on the structure of that element. At times it corresponds to the number of electrons in the outermost shells called valence electrons.

Below are the valencies of some elements:

Element                                  Symbol                                   Valency

Aluminium                                Al                                             +3

Argon                                       Ar                                             Nil

Calcium                                    Ca                                            +2

Chlorine                                    Cl                                             -1

Sulphur                        S                                             -2, -4 or -6

Sodium                        Na                                           +1

Magnesium                               Mg                                           +2

Copper                                     Cu                                            +1 or +2

Carbon                                     C                                              -2 or -4

Barium                                     Ba                                            +2

Silver                                        Ag                                            +1

Iron                                          Fe                                             +2 or +3

Valencies have either positive or negative values showing whether electrons are gained or lost. If an element gains electrons, its value is negative but positive when it loses electrons.

Generally, metals exhibit positive valencies while non – metal tend to have negative valencies. Some element exhibit more than one valency. Valency can also be called oxidation number or state.

RADICALS

A radical is a group of atoms having an electric charge either positive or negative which keeps its identity and react as a single unit. Any small group of atoms carrying a negative charge is called an acid radical. Examples of acid radicals include S042-, C032-, N03

The valency of a radical corresponds to the charge it carries.

Radical                                     Formula                                    Valency

Ammonium                                          NH4+                                        +1

Hydroxide                                            0H                                           -1

Trioxonitrate(V)                                   N03                                          -1

Dioxonitrate(III)                                  N02                                          -1

Trioxocarbonate(IV)                           C032-                                            -2

Tetraoxosulphate(VI)                    S042-                                              -2

Hydrogen trioxocarbonate                 HC03                                          -1

GENERAL EVALUATION/REVISION

  1. Define (i) valency (ii) Radical
  2. Write the valency of: a) Oxygen (b) Potassium c) Sulphur d) S042- e) NH4+
  3. Classify the following into physical or chemical changes: a) Rusting of iron b) Fermentation of palm wine c) Evaporation of a salt solution d) Melting of ice

READING ASSIGNMENT

  • New School Chemistry for SSS by O.Y Ababio. Pg 26, 32-33

WEEKEND ASSIGNMENT

  1. The combining power of oxygen is (a)+2 (b)-2 (c)-1 (d)+1
  2. Which of the following is a metalloid?  (a) sulphur (b) iron (c) silicon   (d) carbon
  3. The symbol Au represents (a) silver (b) lead (c) copper (d) gold
  4. Which of the following elements is used as a standard in defining valency?

           (a) oxygen (b) copper (c) carbon (d) hydrogen

  • Which of the following metals is a liquid at room temperature?
  • iron (b) gold (c) tin (d) mercury

THEORY

1.         a.         Define an element.

  •     Write the symbols of the following elements

(i)  Manganese (ii) Caesium     (iii) Cobalt

2.         a.         What are metalloids?

  •     Give two differences between metals and non-metal

WEEK FIVE

TOPIC: COMPOUNDS AND MIXTURES

CONTENT

  • COMPOUND
  • FORMULAE OF COMPOUNDS
  • MIXTURES
  • DIFFERENCES BETWEEN COMPOUNDS AND MIXTURES

COMPOUND

A Compound is a substance which contains two or more elements chemically combined together. A compound is formed as a result of chemical change.

Examples of compounds are

Compound                               Constituent Elements

Water                                       Hydrogen, oxygen

Sand                                        silicon, oxygen

Limestone                                calcium, carbon, oxygen

Common salt                            sodium, chlorine

Ethanol                        carbon, hydrogen, oxygen

PROPERTIES OF A COMPOUND

  1. It has properties different from those of its component elements.
  2. Its formation often requires large amount of heat.
  3. It cannot be separated by physical means.
  4. The components of a compound have a fixed ratio by mass.
  5. Compounds are homogenous.

EVALUATION

  1. Define a compound.
  2. Give three examples of a compound.

FORMULAE OF COMPOUNDS

When an element exists as a molecule, a number is written as a subscript after the symbol of that element. For example, hydrogen is written as H2 and oxygen as 02.

A compound contains whole numbers of atoms of the component elements. Its molecular formula is written as follows.

  1. The symbols of all the component elements are written close together as a group.
  2. The number of atoms of each component element is written as a subscript after the symbol of that element.

Examples

            Compound                             Formula

            Hydrochloric acid                      HCl

            Water                                       H20

            Ammonia                                  NH3

            Carbon(IV)oxide                       C02

            Lead II chloride                        PbCl2

            Calcium trioxonitrate(V)           Ca(NO3)2

WRITING FORMULA FROM VALENCIES

Formulae of compounds can be deduced from the valencies of the component elements or radicals, following the rules below.

  1. Write the symbols of the element or radicals in a compound
  2. Write their valencies below the symbols of elements/radicals
  3. Exchange their valencies.
  4. Now write the formula of the compound bringing the symbols of the element or radicals together

Examples

  1. Write the formula of sodium tetraoxosulphate(VI)

Rule 1                          Na                                S04

Rule 2 & 3                    1                                  2

Rule 4                          Na2S04

  • Write the formula of calcium chloride

Rule 1                          Ca                                Cl

Rule 2 & 3                    2                                  1

Rule 4                          CaCl2

EVALUATION

  1. Write the formulae of; (i) tetraoxosulphate(vi) acid (ii) Magnesium Chloride
  2. State three properties of a compound

MIXTURES

A mixture contains two or more constituents which can easily be separated by physical methods.

Examples of mixtures with their constituents are outlined below:

Mixture                                                              Constituents

Air                                                                    Oxygen, Carbon (iv)oxide, nitrogen, rare gases, dust, moisture

Soil                                                                   Sand, clay, humus, water, air, mineral salts

Urine                                                                urea, water, mineral salt

Palm wine                                                         water, sugar, alkanol, mineral salts, vitamins, yeast, protein, fat

Coca-cola                                                          water, sugar, cola, CO2

Milk                                                                  water, sugar, fat, protein, mineral salts, vitamin

Sea water                                                         water, mineral salts, bacteria, remains of organic matter

Brass                                                                copper and zinc

DIFFERENCES BETWEEN MIXTURES AND COMPOUNDS

      Mixture                                                      Compound

1.         It may be homogenous                        It is always homogenous.

            or heterogeneous.

2.         It can be separated into                       It cannot be separated into its

            its constituents by physical                   components by physical means.

            means

3.         The constituents can be                       The components are present in a

            added in any ratio by mass                  fixed ratio by mass. Hence a

            Hence a mixture cannot be                  compound can always be repre-

            represented by a chemical                    sented by a chemical formula.

            Formula.

4.         The properties of a mixture                  The properties of a compound

            are the sum of those of its                   are entirely different from those

            individual constituents.                         of its components.

EVALUATION

  1. List five (5) compounds and their formulae
  2. What is a mixture?
  3. State four differences between compound and mixture

READING ASSIGNMENT

  • New School Chemistry for SSS by O.Y Ababio. Pg 11, 36 to 37

GENERAL EVALUATION/REVISION

  1. State the valency of the following elements and radicals: Na, K, S, O, SO42-, NO3, CO32-
  2. Write the formula of: a) Lead (ii) tetraoxosulphate (vi) b) Hydrochloric acid c) Sodium trioxocarbonate (iv) d) Calcium hydroxide

WEEKEND ASSIGNMENT                                

  1. Which of the following is a mixture? (a) water(b) sugar(c) milk (d) starch
  2. Which of the following is a compound?  (a) water (b) soil (c) diamond (d) graphite
  3. Which of these formulae represents ammonia? (a) NH3 (b) NH4+ (c) NH2 (d) CH4
  4. The formula for sand is (a) C02 (b) SO2 (c) NO2 (d) SiO2
  5. Compounds are always (a) heterogeneous (b) homogeneous (c) homogeneous or heterogeneous (d) chemogeneous

THEORY

1.         a. Define (i) Compound (ii) Mixture

            b. Give two examples each of compound and Mixtures

2.         a. State four differences between compound and mixture

            b. What is the formula of

i) tetraoxosulphate (vi) acid

ii) Ammonium sulphide

            iii) Sodium tetraoxophosphate

WEEK SIX

TOPIC: STANDARD SEPARATION TECHNIQUES

CONTENT

  • STANDARD SEPARATION TECHNIQUES

STANDARD SEPARATION TECHNIQUES

The importance of separating a mixture into its constituents cannot be over emphasized since most substances are needed in their pure form. There are many standard separation techniques. Some of these separating techniques are filtration, centrifugation and decantation. Others include sieving, magnetic separation and sublimation, evaporation, crystallization, fractional precipitation, distillation, fractional distillation, using separating funnel and chromatography.

FILTRATION

Filtration is a separation technique that involves separating an insoluble solid from liquid using a filter. For example, a mixture of chalk particles in water can be separated using filtration technique. Filtration is used in industries such as water purification plants and breweries.

CENTRIFUGATION

                                   A CENTRIFUGE MACHINE

Centrifugation is a standard separation technique used to separate a mixture of insoluble solid from liquid by using a centrifuge. A centrifuge is a machine which can spin test tubes containing suspensions at high speed. Centrifugation is often used when there is only a small amount of material. In hospitals, blood samples are centrifuged to separate the blood cells from the plasma.                                        

DECANTATION

Decantation is a separation technique used to separate a mixture containing insoluble solid from a liquid. This is done when the mixture is allowed to settle down with the upper clear liquid carefully poured or decanted into a clean container thereby leaving the lower solid in the container originally containing the mixture. This is a quick but inaccurate method of separating the components of a mixture.

EVAPORATION

Evaporation is a separation technique used to recover soluble solute from its solvent. For example salt can be separated from salt solution by evaporation.

A Salt Evaporation Pond

Salt is produced in the San Francisco area mainly by solar evaporation, where seawater is fed into large ponds that are gradually evaporated by the sun and the wind. After the water is evaporated, the salt is collected.

Evaporation is used in salt –making industries.

CRYSTALLIZATION

Crystallization is used to obtain pure crystals of salts which decompose easily on heating from its solution. The solution is concentrated by heating. It is allowed to cool down and crystals start to form. To induce crystal formation:

  • add crystals of the salt (seedling)
  • scratch the inside of the container with a glass rod

Crystallization is used in industries where purity of the product is important, such as in drug industries and sugar industries.

FRACTIONAL CRYSTALLIZATION

It is used to separate two or more solutes (solids) which are present in the same solution. The solutes to be separated must have different solubilities at different temperatures. Starting from a particular temperature, as cooling of the solution of those solutes takes place, the crystals of the relevant solutes appear leaving the other solutes in the solution.

EVALUATION

  1. Explain briefly the following methods of separation of mixtures: (a)     Filtration (b) Decantation                     (c) Centrifugation
  2. Explain how a pure sample of copper (II) tetraoxosulphate (VI) crystals can be obtained from its solution in the laboratory.
  3. How would you separate a mixture of PbCl2 and NaCl

PRECIPITATION

In precipitation, a difference in the solubility of a solid in two different miscible liquids is used. For example, FeS04 is soluble in water but not on ethanol. If ethanol is added to a solution of FeS04 in water, the FeS04 will be precipitated out of the solution and filtered out.

SUBLIMATION

Sublimation is the change of state from solid to gas directly on application of heat. Examples of substances that sublime are iodine and ammonium chloride. Sublimation can be used to separate these substances. The pure crystal recovered is the sublimate.

DISTILLATION

This is used to recover a solvent from a solution. It involves vapourising a liquid and then condensing the vapour into a liquid called distillate. The solute and other impurities remain in the distillation flask. It is used in gin and water distilleries to manufacture gin and distilled water.

FRACTIONAL DISTILLATION

This is used to separate a mixture of two or more miscible liquids based on their boiling points. When two liquids have boiling points that are very close (less than 100oC the use of simple distillation becomes difficult. A fractionating column is inserted into the distillation flask. It is used to separate crude oil into fractions, separation of liquid air into oxygen and nitrogen, manufacture of spirits and to separate benzene and methyl benzene mixture.                  

EVALUATION

1.    State the major difference between distillation and fractional distillation in terms of (a) Features of the apparatus (b) Mixtures to be separated

2.   Explain the following separation techniques

  • Precipitation
  • Sublimation

SEPARATING FUNNEL

This is used to separate immiscible liquids. It depends on the densities of the two liquids. The less dense will be on top and the denser below. It is used to separate water and kerosene

SIEVING

This is used to separate solid particles of different sizes. Particles smaller than the size of the sieve (mesh) pass through leaving behind particles of larger sizes. It is used in gold and diamond mines and in garri industries.

MAGNETIC SEPARATION

This is used to separate magnetic substances from non-magnetic particles. It is used in mining and steel industries. It can be used to remove magnetic impurities from tin ores. It can be used to separate iron filings from sulphur powder.

CHROMATOGRAPHY

This method uses a solvent moving over an adsorbent medium (paper) which is porous to separate mixtures of solutes.

A chemist uses liquid chromatography to analyze a complex mixture of substances. The chromatograph utilizes an adsorptive medium, which when placed in contact with a sample, adsorbs the various constituents of the sample at different rates. In this manner, the components of a mixture are separated. Chromatography has many valuable applications, such as determining the level of pollutants in air, analyzing drugs, and testing blood and urine samples.

Types

  1. Paper chromatography
  2. Thin layer chromatography
  3. Gas chromatography
  4. Column chromatography

In paper chromatography, a solution, such as ink, is spotted into the paper near one end. The paper is dipped into an appropriate solvent such as water or ethanol in a closed air-tight jar. The solvent moves up the paper. The paper is removed and dried. The different spots on the paper show the different substances the solution (ink or dye) contains.

It is used in medicine to analyze blood. In industry, it is used to identify petroleum fractions. It is also used in scientific research.

CRITERIA FOR PURITY

  1. The melting point and boiling point of a pure substance are fixed but change in the presence of impurities. Impurities lower the melting point of a substance and increase its boiling point
  2. A pure substance gives one spot on a paper chromatogram.

GENERAL EVALUATION

  1. Explain the following separation techniques. Magnetic separation, paper chromatography and sieving
  2. Describe how you would separate a mixture of NaCl, PbCl2 and NH4Cl
  3. What method can be applied to separate a mixture of iron filings and sulphur
  4. Mention two criteria for purity of a substance.

READING ASSIGNMENT

  • New School Chemistry for SSS by O.Y Ababio.Pg 16 to 20

WEEKEND ASSIGNMENT

  1. A mixture of oil and water can be separated by (a) sublimation (b) evaporation to dryness 

(c) using a separating funnel (d) fractional distillation

  • Fractional distillation is used to separate (a) an insoluble substance from a soluble volatile substance (b) liquids with differing boiling points (c) gas, liquid or solid impurities from a mixture (d) liquid with close boiling points
  • Which of the following separating techniques can be used to separate a mixture of iodine and sodium chloride? (a) distillation (b) evaporation  (c) sublimation  (d) decantation
  • Which of the following is not a type of chromatography ?(a) thin layer (b) gas  (c) paper 

(d) glass

  • Which of the following is a quick but inaccurate way of separating mixture? (a) decantation (b) evaporation  (c) filtration  (d) distillation

THEORY

  1. Explain briefly the following separation techniques (a) evaporation (b) filtration (c) fractional distillation
  2. Mention two criteria for purity of a substance.

WEEK SEVEN

TOPIC: PARTICULATE NATURE OF MATTER

CONTENT

  • ATOMS AND MOLECULES
  • IONS
  • DALTON’S ATOMIC THEORY
  • MODIFICATIONS OF DALTONS ATOMIC THEORY

ATOMS AND MOLECULES

Matter is made up of discrete particles. The main ones are atoms, molecules, and ions.

An atom is the smallest part of an element which can take part in a chemical reaction.

A molecule is the smallest particle of a substance that can exist alone and still retains the chemical properties of that substance. Molecules are made up of atoms.

Atomicity of an element is the number of atoms in one molecule of the element.

We have monatomic, diatomic and triatomic for those elements that contain one atom, two atoms and three atoms respectively in their molecules.

Examples:

Element                                              Atomicity

Hydrogen                                             Diatomic

Oxygen                                                Diatomic

Nitrogen                                               Diatomic

Neon                                                    Monoatomic

Helium                                                  Monoatomic

Argon                                                   Monoatomic

EVALUATION

  1. Define an atom.
  2. Give two examples of diatomic molecules.

IONS

An ion is an atom or group of atoms which carries an electric charge. Such groups of atoms that carry either a positive or negative charge are called RADICALS.

An acid radical is thus a small group of atoms carrying a negative charge that keeps its identity. Examples include S042-, N03 e.t.c.

Generally ions are grouped as cations and anions. Cations are positively charged ions e.g Ca2+, Na+, NH4+ e.t.c.

Anions are negatively charged ions e.g.. C032-, S042-, Cl, OH, etc.

EVALUATION

  1. What are ions?
  2. State the cation and anion present in (I) H2S04   (ii) NaCl (iii) FeS04

DALTON’S ATOMIC THEORY

John Dalton, British Physicist and Chemist (1808) proposed the atomic theory thus: 

  1. All elements are made up of small indivisible particles called atoms.
  2. Atoms can neither be created nor destroyed in any chemical reaction.
  3. Atoms of the same elements are exactly alike in aspect and are different from atoms of all other elements.
  4. Atoms of different elements can combine in simple whole number ratios to form compounds.
  5. All chemical changes result from the combination or separation of atoms

MODIFICATIONS OF DALTON’S ATOMIC THEORY

Due to new discoveries in the twentieth century, Dalton’s atomic theory cannot hold in its entirety. There is need for its modification.

  1. The first statement has been proved wrong by Rutherford’s discovery of protons, electron and neutrons as constituents of the atom. An atom is not an indivisible solid piece.
  2. The second statement still holds good for ordinary chemical reactions. During nuclear reactions, however, the nucleus can be broken into simpler atoms giving out large amount of heat (nuclear fission). This destroys the atoms involved.
  3. The discovery of isotopes makes the third statement unacceptable. Chlorine for example has two atoms with different nucleus content and hence different relative atomic masses although the same proton numbers.
  4. The fourth statement is true only for inorganic compounds which contain a few atoms per molecule. Carbon forms very large organic molecules such as proteins, starch and fats which

contain thousands of atoms.

GENERAL EVALUATION/REVISION

  1. State the modifications of the Dalton’s atomic theory.
  2. A mixture contains propanone, ethanol and water with boiling point of 560C, 780C and 1000C respectively.
  3. What method will be used to separate the liquids
  4. Name the first liquid that will distil over. Explain your answer
  5. Name an industrial process that uses fractional distillation

READING ASSIGNMENT

  • New School Chemistry for SSS by O.Y Ababio. Pg 25-26

WEEKEND ASSIGNMENT

  1. Which of the following is not a constituent of the atom (a) proton  (b) electron (c) neutron

 (d) isotope

  • Which of the following statement about an atom is not correct? (a) it is indivisible (b) it is destructible in some cases (c) it is the smallest part of a substance that takes part in a reaction (d) it is made up of protons, neutrons and electrons
  • Which of the following is a liquid at room temperature? (a) copper (b) gold  (c) mercury

 (d) silver

  • How can you separate a mixture of iron filings and sulphur powder? (a) distillation 

(b) chromatography (c) magnetization  (d) evaporation

  • What is the atomicity of neon? (a) monoatomic (b) diatomic (c) triatomic  (d) polyatomic

THEORY

  1. Give any two postulates of the Dalton’s atomic theory.
  2. (a)        Differentiate an atom from a molecule.

(b)       How will an atom become an ion?

WEEK EIGHT

IUPAC NOMENCLATURE OF CHEMICAL COMPOUNDS

CONTENT

Naming of:

         —- binary compounds

         —- radials and compounds having elements with variable oxidation numbers.

         —- tertiary and quartenary compounds.

         —- compounds with cations replaced with hydrogen.

NAMING OF BINARY COMPOUNDS

Nomenclature: This is the system of naming chemical compounds. The system is called IUPAC (International union of pure and applied chemistry). The naming is determined by the constituent elements in the compound and the oxidation number if necessary.

In naming binary compounds (compounds with only two elements), electropositive elements (cations) are usually named first while the electronegative elements (anions) come last with a modification of the name end with – ide.

Examples:

    Formula               IUPAC name

      MgO                  Magnesium oxide

      H2S                    Hydrogen sulphide

      NH4Cl                Ammonium chloride

      NaH                   Sodium hydride

But in cases where the two elements involved are non-metals, the above rule is not followed. For example, H2O (water) NH3 (ammonia) and PH3 (phosphine)

EVALUATION

Name the following compounds: (a) NaCl (b) CaO (c) H2O2.

NAMING OF RADICALS AND COMPOUNDS HAVING ELEMENTS WITH VARIABLE OXIDATION NUMERS

Radicals (group of atoms of element carrying electrical charge) are treated as a single element when naming their compounds.

             Examples of radicals with their names are as follows:

               Radical                    IUPAC NAME

               NH4+                       Ammonium ion

               OH‑                                        Hydroxyl ion

But in naming acid radicals, the oxidation number of elements is indicated by Roman numbers in bracket.

    Example:

     Formula             IUPAC

     NO2‑                  Dioxonitratei(iii) ion

     NO3                   Trioxonitrate(v) ion

     CO32-                 Trioxocarbonate(iv) ion.

Also the compounds having elements with Roman numbers in bracket indicating their oxidation numbers in that compound

    Examples

     Formula                   IUPAC

      FeO                          Iron (ii) oxide

      Cu2O                        Copper (i) oxide

      MgCO                   Magnesium trioxocarbonate (iv)

EVALUATION

  1. Name the following compounds (a) Fe2O3    (b) CuO
    1. What are the oxidation numbers of Fe and Cu in (1) above?

NAMING TERTIARY COMPOUNDS AND QUARTENARY COMPOUNDS.

These are compounds containing more than two elements.

      Examples are oxo-acids, normal salts, and acid salts.

         Acid                                 IUPAC   

         HNO                            Trioxonitrate(v) acid

         H2SO4                             Tetraoxosulphate (vi) acid

         H3PO4                             Tetraoxophospate (v) acid                                    

      Examples of Normal Salts.

        Normal salts                      IUPAC

         KNO3                               Potassium trioxonitrate (iv)

         NaSO4                             Sodiumtetraoxosulphate (vi)

         CuCO3                              Copper (ii) trioxocarbonate (iv)

EVALUATION 

  1. Determine the oxidation number of: a) C in H2CO3 b) Mn in KMnO4 c) Cu in CuSO4
  2. Name the compounds in 1 above


NAMING OF COMPOUNDS WHOSE CATIONS HAS BEEN PARTIALLY REPLACED WITH HYDROGEN IONS.

In naming compounds whose cations have been partially replaced with hydrogen ion, the cations is named first followed by hydrogen, then the radicals present indicating the roman number standing for the oxidation number of the element that is combined with oxygen to form the radical.

E.g Formula                                IUPAC

NaHSO4                                       Sodium hydrogen tetraoxosulphate (vi)

KHSO3                                        Potassium hydrogen trioxosulphate (iv)                      

GENERAL EVALUATION/REVISION:

  1. Determine the following oxidation number of a) C in LiHCO3 b) S in KHSO4 and name the compounds
  2. Write the chemical formula of the following compounds a) Oxochlorate (I) acid b) Iron (ii) tetraoxosulphate (VI) pentahydrate
  3. State the uses of the following laboratory apparatuses a) Condenser b) Kipp’s apparatus c)Tripod stand

READING ASSIGNMENT

  • Practical Chemistry for Senior Secondary Schools By Godwin O. Ojokuku  pg 20-28.

WEEKEND ASSIGNMENT

  1. The compound Na2S is called ____ (a) Sodium (ii) sulphate (b) Sodium sulphur (c) Sodium sulphide (d) Sodium sulphite.
  2. The formula of sulphur (iv) oxide is (a) SO4 (b) SO2 (c) S2O4 (d) S4O2
  3. Ammonium chloride can be written as (a) NH4Cl (b) NH3Cl2 (c) NH4HCl

(d) NH4OH

  1. The IUPAC name of NaHSO4 is (a) Sodium bicarbonate (b) Sodium tetraoxosulphate (vi) acid (c) Sodium sulphate (c) Sodium hydrogen tetraoxosulphate (vi)
  2. Which of the following compounds have cation with variable oxidation state.

(a) FeO3 (b) ZnCO3   (c) CuO (d) KU

THEORY

  1. Name the following compounds (a) Fe2O3 (b) KMnO4    (c) KClO3
  2. Calculate the oxidation number of (a) Sulphur in H2SO4 (b) Carbon in CuCO3       

Chemistry Lesson Note for SS1 First Term – Edudelight.com

WEEK NINE

ATOMIC NUMBER, RELATIVE ATOMIC MASSES, ISOTOPES AND CALCULATIONS

CONTENT

  • ATOMIC NUMBER AND MASS NUMBER
  • ISOTOPES
  • CALCULATIONS OF RELATIVE ATOMIC MASS


CONSTITUENTS OF AN ATOM

Atoms are made up of sub-particles. Protons, electrons and neutrons. Proton has a positive charge, electron has a negative charge and neutron has no charge.

Atomic number and mass number

The atomic number of an element is the number of protons in the nucleus of its atom.

Mass number or atomic mass of an element is the sum of the number of protons and neutrons in the nucleus of its atom.

Mass Number = Number of proton + Number of neutron

An element X can be represented as

                                    ZXA

where               A= Atomic mass or mass number

Z= Atomic number

e.g.      40        mass no = 40

                Ca

  • atomic no = 20

EVALUATION

  1. State the constituents of an atom.
  2. What is the number of proton in the following elements?

(a)        11B       (b)        12C

  • 6

ISOTOPES

Isotopy is the occurrence of atoms of elements having the same atomic number but different mass numbers. This is due to the difference in the number of neutrons present in the atoms. The atoms that exhibit isotopy are called ISOTOPES.

Examples of atoms that exhibit isotopy are chlorine 35Cl and 37 Cl

Carbon-  12 C, 13 C  and 14 C

Potassium – 39K19   and   41K19             

Oxygen –  16O16    and 18O16                                             

EVALUATION

  1. Define isotopy.
  2. Write the isotopes of chlorine.

CALCULATION OF RELATIVE ATOMIC MASS

The following is an example of calculation of relative atomic mass of an element from percentage abundance of its isotopes.

1. X is an element which exists as an isotopic mixture containing 90% of 39X19 and 10%  of 41X19

  1. How many neutrons are present in the isotope 41X                                                                               
  2. Calculate the mean relative atomic mass of X

Solution

  1. Neutrons in  41X19

                        =          41-19 = 22

b.         R.A.M   =          90        x          39        +          10        x          41

  1. 100

=          90        x          39        +          41        x          10

                                    100

=          3920    =          39.20

100

EVALUATION

  1. How many neutrons are present in the isotope 37Cl17 ?
  2. A given quantity of chlorine contains 75% 35Cl17, and 25% 37Cl17, determine the relative atomic mass of chlorine.

CALCULATIONS

  1. The following are more examples of calculations of relative atomic masses of elements.
  2. An element Y exist in two isotopic forms 39Y18 and 40Y18 in the ratio 3:2 respectively. What is the relative atomic mass of the element?

SOLUTION                            

R.A.M of Y        =          3          x          39        +          2          x          40

                                    5                      1                     5                       1

                        =         0.6        x         39         +         0.4        x          40

                        =        23.4       +       16

                        =       39.4  

  •  An element with relative atomic mass 16.2 contains two isotopes 16P8 with relative abundance 90% and mP8 with relative abundance 10%. What is the value of m?

SOLUTION

            16.2 =  90 x 16 + 10 x m

                                  100

             16.2 = 9 x 16  +   m

                          10           10

            16.2 = 144   +   m

                        10         10

            16.2 = 144  +  m

                              10

            16.2 x 10 = 144 + m

            162   = 144 + m

            162 – 144 = m

                  18 =   m

The value of m is 18

GENERAL EVALUATION/REVISION

  1. Consider the atoms represented  below:

qX                      rX

p                      p

  1. State the relationship between the two atoms.
  2. What is the difference between them?
  3. Give two examples of other elements which exhibit the phenomenon illustrated.
  4. State the number of electrons, protons and neutrons present in the following atoms/ions
  5. Ca b) S2- c) Al3+ d) P
  6. If an element R has isotopes 60% 12R6 and 40% xR6 and the relative atomic mass of R is 12.4, find x.

READING ASSIGNMENT

  • New School Chemistry for SSS by O.Y Ababio. Pg 48-49

WEEKEND ASSIGNMENT

  1. The atomic number of an element is precisely

(a) the number of protons in the atom (b) the number of electrons in the atom (c) the number of neutrons in the atom

  • An atom can be defined more accurately as (a) the smallest indivisible parts of an element that can take part in a chemical reaction (b) the smallest part of an element that can take part in a chemical reaction (c) a combination of protons, neutrons
  • The mass number is (a) proton number + neutron number (b) electron number + proton number  (c) neutron number + electron number
  • Calculate the relative atomic mass of an element having two isotopes 107 Ag and 109Ag in the ratio 1:1  (a)106  (b)107 (c)108
  • An element X has two isotopes 18.8X and 15.8X in the proportion of 1:9 respectively. Find the relative atomic mass of X (a)16.1  (b)13.6  (c)16.8

THEORY

1.         (a)        Define the term isotopy.

(b)        Determine the number of electrons, protons and neutrons in each of the following: 39K19, 63.5Cu29

2.         If an element R has isotopes 60% of 12R6 and 40%  xR6 and the relative atomic mass is 12.4, find x.

WEEK TEN

TOPIC: STRUCTURE OF THE ATOM

CONTENT

  • Orbitals of The Atom
  • Electronic Structure Of the Atom
  • Filling Of Electrons in to Orbitals
  • Quantum Numbers

ORBITALS OF THE ATOM

The region in space within which there is maximum possibility of finding an electron in an atom is called an ATOMIC ORBITAL. We have s, p, d, and f orbitals.

Shapes of s and p orbitals are as follows:                               

                       s-orbital                                           

px orbital

                                               py orbital                                                                                      pz    orbital

EVALUATION

  1. Define atomic orbital
    1. State the shape of (i) S-orbital (ii) P-orbital.

ELECTRONIC STRUCTURE OF THE ATOM

With the knowledge of atomic orbital the spectra of more complex atoms than hydrogen atom can be explained as follows:

a) that within a given principal quantum number or energy level, there are sub energy levels, i.e. energy levels otherwise called K,L,M,N,O,P AND Q shells have sub-energy levels otherwise called s,p,d and f orbitals

(b) The total number of sub-shells within a shell is given by n2

while the total maximum number of  electrons is given by 2n2 where n is  the number of  enregy level.

Energy Level                             Number of orbitals                    Maximum No of electrons

n = 1(K- shell)                              12 =1                                         2´12 =2

 n =2 (L- shell)                              22 = 4                                       2´22 = 8

 n = 3 (M- shell)                          32 = 9                                       2´32 = 18

 n = 4 (N- shell)                           42 =16                                      2´ 42 = 32

n = 5 (O- shell)                            52 = 25                                     2´ 52 =50

n = 6 (P-shell)                              62 = 36                                     2´62 =72

n = 7 (Q – shell)                           7= 49                                      2´72 = 98                    

(c) In a given orbital there could be a maximum of only two electrons and electron in all orbitals of the same type within a principal quantum number possess equal energies.

(d) The electrons in the different sub- shells or orbitals within a principal quantum number do not all have equal energies.

The gradation of energies of orbitals is as follows:

1s< 2s<2p<3s<3p<3d<4s<4p<4d—

EVALUATION

  1. State the first five energy levels.
  2. Calculate the total no of electrons when n is equal to (i) 2 (ii) 4.

FILLING OF ELECTRONS IN ORBITALS

In filling electrons into the atoms of elements, considerations are given to the conditions laid down by Aufbau Principle, Pauli exclusion principle and Hund’s rule of maximum multiplicity.

AUFBAU PRINCIPLE states that electrons go in to fill orbitals of lower energy first before filling orbitals of higher energy and each orbital may hold up to two electrons.

PAULI EXCLUSION PRINCIPLE states that no two electrons have identical sets of the four quantum numbers {n, l, m and s in an atom}.

HUND’S RULE OF MAXIMUM MULTIPLICITY state that in filling degenerate orbitals with electrons, electrons go in singly first before pairing up occurs.

EVALUATION

State the following principle

{a} Aufbau Principle {b} Hund’s rule.

QUANTUM NUMBERS

Studies show that the energy of an electron may be characterized by four quantum numbers. These are

{1}The principal quantum number represented by n with integral values of 1,2,3,4 e.t.c.

{2}The subsidiary or Azimuthal quantum number represented by l with integral values 

      ranging from O to (n-1).

(3) The magnetic quantum number represented by m with integral values ranging

      from –l to +l.

4. The spin quantum number represented by s with integral values – 1/2 and = 1/2.

Element           Atomic Number         Electronic configuration.

H                           1                               1S1

He                          2                              1S2

Li                           3                              1S2 2S1

Be                          4                              1S2 2S2

B                            5                              1S2 2S2 2P1

C                            6                              1S2 2S2 2P2

N                            7                              1S2 2S2 2P3

O                            8                              1S2 2S2 2P4

F                             9                              1S2 2S2 2P5

Ne                         10                              1S2 2S2 2P6

Na                         11                              1S2 2S2 2P6 3S1

Mg                         12                              1S2 2S2 2P6 3S2

Al                           13                             1S2 2S2 2P6 3S2 3P1

Si                            14                             1S2 2S2 2P6 3S2 3P2

P                             15                             1S2 2S2 2P63S233P3

S                             16                             1S2 2S2 2P63S2 3P4

Cl                            17                             1S2 2S2 2P6 3S2 3P5

Ar                            18                             1S2 2S2 2P6 3S23P6

K                             19                             1S2 2S2 2P6 3S23P6 4S1

Ca                            20                             1S2 2S2 2P6 3S23P6 4S2

GENERAL EVALUATION

  1. State the four quantum numbers.
  2. Write the electronic configuration of the following a) Mg b) S2- c) Ca2+ d) Si

READING ASSIGNMENT

  • New School Chemistry By O.Y. Ababio pg 49-54.

WEEKEND ASSIGNMENT

1.  Which of the following orbitals is spherical in shape?

  • s (b) p (c) d (d) f

2. Which of the following shells have a maximum of eight electrons ?

  • k (b) l (c) m (d) n

3. 1s2 2s2 2p6 3p1 is the electronic configuration of

  • potassium (b) calcium (c) sodium  (d) aluminum.

4. “No two electrons have identical sets of four quantum numbers”. This statement is

  • Aufbau principle (b) Pauli exclusion (c) Hund’s rule (d) Rutherford’s model.

5. Which of the quantum number is represented by L?

  • principal quantum no (b) subsidiary quantum no (c) magnetic quantum

(d) spin quantum.

THEORY

  1. State the following principle (a) Pauli exclusion principle. (b) Aufbau principle.
  2. Write the electronic configuration of

(a) Oxygen

(b) Calcium (c) Chloride ion (Cl) (d) Aluminum ion (Al3+)

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