Basic Science Plan Notes of Lesson Basic 9 (JSS3) 2nd Term

JSS3 Second term Lesson Notes. Basic 9 Free Basic Science Plan for Secondary School. Family trait, Acid, bases and salts,Radioactivity.

BASIC SCIENCE SCHEME OF WORK BASIC 9 2ND TERM

WEEKS	TOPICS	LEARNING OBJECTIVES: At the end of the lesson the students should be able to:
1	Revision of last term work	Revision topics/ welcome test
2	Family trait	Definition of trait and differences between hereditary and non-hereditary trait
3	Activity series	Meaning of activity series , equipment to show reacting capacity of various metals and non-metals, accordingly
4	Acid, bases and salts I	Define acid, bases and salts
5	Acid m bases and salts II	Prepare a simple salt by different method
6	Continuous assessments	Evaluation
7	MID TERM BREAK	Mid-term Test
8	Continuous assessments	Evaluation
9	Radioactivity	Explain the meaning of radioactivity distinguish between the three basic radioactive emissions, enumerate the importance and hazards , compare and contrasts natural and artificial radioactivity
10	Depletion of the ozone layer	Describe the ozone layer and indicate its location, explain the economic importance, highlights the factors
11	Revision	Revision
12	Examination	Markings

---

WEEK:          ONE                                                              

TOPIC:          REVISION OF LAST TERM’S WORK/ WELCOME TEST

WEEK:        2                 DAY:                              SUBJECT:

DATE:                            TOPIC:  

SUBTOPIC:                    PERIODS:                      DURATION:

LEARNING OBJECTIVES:       At the end of the lesson, pupils should be able to

1. Define family trait
2. State types of trait
3. State the types of character of trait  
4. Explain gene and differences
5. State the important of family trait   

KEY VOCABULARY WORDS:

INSTRUCTIONAL MATERIALS:

CONTENT:

 FAMILY TRAIT

A family trait is a genetic likeness that is passed through the parents” genes to their children or offspring. The traits that are being inherited are present in form of genes. Genes are the hereditary unit.

The characters or traits that can be passed from the parents to the offspring include the following;

I- Skin colour( dark or fair)

ii-Height (tallness or shortness)

iii- Colour of the skin, hair, eye iris colour

Iv-Shape of the face, eye ball, mouth, eyelashes, lips, forehead, head, ears etc

v- Method or style of walking.

Vi-Quantity of hairs on the head, body, eyebrow and eye lashes.

Vii-Voice

Viii-Abnormalities such as albinism, sickle cell anemia, colour blindness, hemophilia.

Dominant Trait

Dominant Trait is trait that keeps on appearing among the family in each successive generation. For instance, if a dominant tall man with dominant gene (TT) Maries a tall woman who has a recessive trait for shortness (Tt). If they produce four children all of them will be tall. This shows that the gene for tallness is dominant over the gene for shortness.

Recessive Traits are those traits that are still present in an organism but do not appear physically because of dominant gen e may suddenly appear in successive generation. For example, if a tall man Maries a short woman may not produce any short child. But their children the recessive traits or genes may produce short children in the second generation.

Differences between Dominant Gene and Recessive Gene  

Dominant Gene	Recessive Gene
1.It is able to express itself even the presence of recessive gene	It is unable to express its effects in the presence of dominant gene
2.It does not require another to produce its effect on phenotype	It produces its phenotypic effects only in the presence of similar gene
3.Dominant gene can form complete polypeptide or enzyme for expressing its  effects	Recessive gene forms an incomplete or defective polypeptide or enzyme so that the expression consists of absence of dominant gene.

IMPORTANCE OF FAMILY TRAIT

-It helps us to understand some genetic disease.

-It can be used to trace family genealogy.

-It can used to trace the manifestation of physical character such as colour of the eye, skin, hair, body size and height

-The knowledge of family trait can be used to detect crime by finger print or DNA test.

-Good trait such as intelligent and other good traits are continuously being transferred in a family.

ASSIGNMENT

1.  Which of the following is not a trait that is transferred genetically from parents to offspring?  A. skin colour B. height C. colour blindness .  D. Smoking

2. Variation like height and skin colour among members of the same family that change from one end of the scale to the other are  A.  recessive  B. Continuous  C. discontinuous. D.  Genotype

3. The genetic make-up of an individual can be altered by  A. the environment B. enzymes  C. exercise  D.  food

4. Which of these is a genetic disease?  A. sickle cell anemia  Malaria  C. headache  Kwashiorkor

5 .Which of the following is not a physical characteristics in  family trait?  A. skin  . B. hair. C. Dentition  D. height

6. A trait that appears in successive generation is  called   A. recessive  Dominant trait  Physical trait  D. genotype

7. Family traits are important to all of the following except in   A. intelligence. B.  Disease control  C. resemblance  D. hunger control

8a. Define family trait.

b. state two significance of family traits to intending couples

c. State two differences between dominant and recessive genes

d. state five examples of traits that can be transferred from parents to offspring.

---

WEEK:        3                 DAY:                              SUBJECT:

DATE:                            TOPIC:  

SUBTOPIC:                    PERIODS:                      DURATION:

LEARNING OBJECTIVES:       At the end of the lesson, pupils should be able to

1. RELATIVE ABUNDANCE AND CHEMICAL CHARACTERISTICS OF METALS,
2. COMPOUNDS OF METALS AND PRINCIPLES OF EXTRACTION OF METALS
3. SODIUM-EXTRACTION, PROPERTIES
4. COMPOUNDS OF SODIUM AND USES OF SODIUM

KEY VOCABULARY WORDS:

INSTRUCTIONAL MATERIALS:

CONTENT:

ACTIVITY SERIES ( METALS AND NON-METALS )

PERIOD 1: : RELATIVE ABUNDANCE OF METALS AND CHEMICAL CHARACTERISTICS

RELATIVE ABUNDANCE

Metals are widely distributed in the earth’s crust either as compounds or in the free metallic form. More than 80 of the known elements are metals except for metals like silver, gold, and platinum, most metals are not found free in nature. They are rather too reactive to exist as free elements. They are more often found as compounds in the form of ores. These ores can exist either as the oxides, hydroxides, trioxocarbonates, sulphates, sulphides, chlorides or nitrate of the metals. Some of the metals are also found in the form of solutions because their stable compounds are stable.

The very reactive metals for example sodium and potassium usually found combined with other elements. For example they are found as chlorides or carbonates which are very stable compounds. Moderately reactive metals, such as zinc and lead, are usually found as oxides or sulphide while the least reactive metals are usually found in un combined state, for example, gold which is found almost entirely as the free metals.

CHEMICAL CHARACTERISTICS OF METALS

1. When metals react, they ionize by loss of electrons to form cations such as Na+, Ca²+ and Al³⁺, hence they are reducing agents.
2. A metal reacts with oxygen to form one or more oxides e.g Na₂O, MgO, FeO, Fe₂O₃, Fe₃O₄, CuO, Cu₂O etc. Oxides of metals are generally basic.
3. Metals react with dilute mineral acids, such as Hcl and H₂SO₄, to liberate hydrogen (except metals that are below hydrogen in the reactivity series. Zn(s) + H₂SO₄ Zn SO_4(aq) + H₂
4. They form electrovalent (ionic) compounds with non-metals such as chlorine. Ca(s) + Cl₂(g) CaCl_2(s)

Activity Series of Metals

The reactivity of a metal depends on the ease with which its atoms lose electrons; the ease varies from one metal to another. When common metals are arranged in the order of their ability to lose electrons and act as reducing agents, the activity series is obtained.

K

Na

Ca Very Reactive

Mg

Al

Zn

Fe

Sn Moderately Reactive

Pb

(H)

Cu

Hg

Ag Least Reactive

Pt

Au Least reactive (weakest reducing agent)

Of all the metals listed above, potassium K is the most electro positive and hence the strongest reducing agent, white fold, an is the weakest.

The activity series arranges the metals in the order of their ability to react and displace the ions of one another from the solutions of their salts. Generally a metal higher up in the series will displace the ions of metals lower down the series from the solutions of their salts. For instance Zn metal will displace or replace ions of copper in a solution of a copper II salt.

Zn(s) + CuSO_{4 (aq)} Cu(s) + ZnSO_4(aq)

EVALUATION

1. What name is given to the arrangement of metals in order of their ability to lose electrons?
2. From the periodic table, write out 30 elements that are metals.
3. Arrange the following metals in order of increasing reactivity Pb, Al, Sn, Q, Au, and Mg.

PERIOD 2:

COMPOUNDS OF METALS AND PRINCIPLES OF EXTRACTING OF METALS

Metals form different compounds such as oxides, hydroxides, trioxocarbonates(iv), trioxonitrates(v), chloride and sulphides.

Principles of Extraction of Metals

The method of extraction of metals from its ore depends on the metals reactivity. The reactivity of a metal depends on its readiness to lose electrons since they react by forming positivity charged ion. Very reactive metals such as sodium, calcium and aluminium are extracted by electrolysis.

Other metals down the activity series are not so strongly electropositive and their compounds are not stable. They can be extracted from their ores by reduction with coke or carbon few metals e.g. gold occurs freely in nature.

Various methods used in the extraction of metals electrolysis – this is a reduction and oxidation process that is often used for the extraction of very strongly electropositive metals (Na, K Q, Mg).

During electrolysis, metallic ions from the electrolytic solution are deposited as atoms on the cathode by accepting electrons from the cathode.

Reduction of oxides: This is basically a reduction process. These metals exist in their ores as metallic ions which must take up the required number of atoms. This method is used for the extraction of less electropositive metals occur as oxides (Fe₂O₃, Fe₃O₄, SnO₂) and are extracted by the reduction of these oxides with coke or carbon (II) oxides.

Reduction of Sulphides

Some of the less electropositive metals e.g. lead occurs as sulphides e.g Feline (Pbs), the sulphide is roasted in air to convert it to the oxide which is reduced to metallic lead by heating with coke in a blast furnace.

2Ps_(s) + 3O_2(s) 2PbO_(s) + 2SO_2(g)

2PbO(s) + C(s) 2P(s) + CO₂(g)

Reduction of Chlorides

Some metals especially alkaline metals are formed as chlorides with their ores (Na+CL-) and are extracted by electrolysis of the chlorides. Sodium collect at the cathode which supplies the electrons, chlorine is formed at the anode.

NaCl Na⁺ + Cl^–

At the Anode:

Na⁺ + e- Na

At the Cathode

Cl^– + e Cl₂

EVALUATION

1. Give two methods of extraction of metals.
2. Explain any of the methods.

PERIOD 3:

ALKALI METALS (GENERAL PROPERTIES)

There is group 1 element: All except Hydrogen are metals. The following are their general properties.

1. They have one electron on their valence shall, hence they ionize to form univalent position ion M M⁺ + e
2. They are reducing agents
3. They tend to be soft and light with relatively 100 melting points.
4. First ionization energy decreases down the group.
5. They all burn in air with characteristics flame colours which are used to identify them.
6. They react with water to form alkaline hence the name alkaline metals sodium react vigorously, potassium vigorously and lithium readily.

SODIUM (Na)

This is the second member of the group I metals. It is very reactive and hence not found free in nature. Sodium occurs in sea water, as chloride, bromide or iodide i.e NaCl, NaBr, NaI.

It occurs as rock salt, NaCl in deposits. Sodium trioxonitrate(v) NaNo₃ is found abundantly in Chile and often called chile salt. It is also found in clay soil as complex trioxosilicate(iv)

EXTRACTION OF SODIUM

Sodium is extracted (in commercial quantity) from fused sodiumchloride by electrolysis. The electrolytic cell used is called down cell as shown below:

The anode is a graphite rod, while cathode is a steel cylinder round the anode together with the electrolyte are contained in a regular steel tank lined inside with fine bricks. The electrolyte i.e. fused sodium chloride with melting point 80 1⁰C is kept melting in the cell by electrical heating. The melting point of sodium chloride can be reduced to about 600⁰C by adding calcium chloride. A cylindrical steel gauze separates the cathode and the anode so that sodium and chloride which are the products of electrolysis can be obtained separately.

At the Cathode

Na⁺ ions takes up an electron each and are reduced to metallic sodium

Na⁺ + e- Na

At the Anode

Cl- ions release an electron each and gets oxidized to atomic chlorine which pair up to form chlorine gas molecules.

Cl^– Cl + e-

Cl + Cl Cl₂

2Na + 2Cl^– 2Na_(s) + Cl_2(g)

Physical Properties of Sodium

1. It is a silvery metallic solid
2. Relative density is 0.98, it therefore floats on water.
3. It is soft and very malleable
4. Melting point is rather low for a metal (97⁰C)
5. It is a good heat and electricity.

Chemical Properties

1. With Air: Sodium tarnishes readily and gets oxide by air to form sodium oxide.

4Na_(s) + O₂ 2Na₂O

The sodium oxide reacts with water vapour in air to form sodium hydroxide

Na₂O_(s) + H₂O_(g) 2NaOH_(aq)

NaOH(aq) slowly absorbs carbon (iv) oxide (CO₂)

In the atmosphere to form crystals of hydrated sodium trioxocarbonate(iv)

2NaOH_(aq) + CO_2(g) Na₂CO₃ + H₂O_(l)

Due to this great affinity of sodium for atmospheric gases it is always stored in a paraffin oil, toluene or naphtha.

If heated in air, sodium burns with golden yellow flame to form Na₂CO₃ (sodium peroxide) and Na2O (sodium oxide) in limited supply of air and oxygen

2Na_(s) + O_2(g) Na₂O_2(s)

4Na_(s) + O_2(g) 2Na₂O₂

With Water:

1. With Water:

Sodium reacts silently with cold water releasing a lot of heat. It darts in water and melts to a silvery bell because of the heat liberated.

2Na_(s) + 2H₂O_(l) 2NaOH_(aq) + H_2(g)

1. With non – Metals

Sodium reacts on heating with hydrogen, halogens, sulphur, phosphorous and most other non-metals except boron, carbon and nitrogen

2Na_(s) + H_(g) 2NaOH_(s)

3Na_(s) + P Na₃P_(s)

2Na_(s) + S_(s) Na₂S_(s)

2Na_(s) + Cl₂ 2NaCl_(s)

It dissolves in mercury to give sodium amalgam

Na_(s) + H_(g) NaH_(g)

With Acid

1. With Acid

Sodium reacts explosively with dilute acids to form hydrogen and salt (dangerous reaction should not be carried out in the laboratory)

2Na_(s) + 2HCl(_aq) 2NaCl_(aq) + H_2(aq)

With Ammonia

1. With Ammonia

Sodium reacts with ammonia to form sodium and hydrogen

2Na_(s) + 2NH_3(aq) 2NaNH₂(_s) + H_2(g)

EVALUATION:

1. Explain why sodium is stored in paraffin oil.
2. With chemical equation only describe the cemical properties of sodium

Test for Sodium

Flame test: compounds containing sodium ions burn with a golden yellow flame in non-luminous flame.

PERIOD 4:

 USES OF SODIUM AND ITS COMPOUNDS

1. Sodium is used in manufacturing compounds like sodium peroxide, sodium cyanide, sodium as well as lead (iv) tetraethyl which is an anti-knock agent in petrol.
2. Liquid sodium is used as coolant in nuclear reactors
3. Mixtures of sodium amalgam and water or sodium and ethanol are useful reducing agents in organic chemistry. Sodium is used in reducing titanium tetrachloride to a metal in the extraction of titanium.
4. Sodium vapour lamps are used in lighting highways and airports because they give bright orange yellow light.

EVALUATION

1. Enumerate the general properties of alkali metals
2. Briefly explain the extraction of sodium metal.

GENERAL EVALUATION

OBJECTIVE TEST:

1. Most reactive metals are extracted from their ore through electrolysis except (a) Na (b) Cu (c) Al (d) Mg.
2. Group 1 metals are good reducing agents becomes (a) they are soft (b) they are light (c) they easily form unipositive ions (d) they have low melting points.
3. In down’s cell used for the extraction of sodium metal, the anode and the cathode are screened with gauze diagram in order to: (a) obtain screened products (b) obtain cheap products (c) separate the products from reacting (d) obey conventional rule electrolysis
4. Which of these compounds is not an alkali? (a) sodium hydroxide (b) aqueous ammonia (c) magnesium hydroxide (d) potassium hydroxide.
5. Metals react with oxygen to form any of these oxide except (a) acidic oxides (b) basic oxides (c) peroxides (d) amphoteric oxides

ESSAY TEST:

1. (a) Discuss the reasons why some metals occur as free elements in nature while others occur in combined forms. Give two examples each type.
2. Draw the electrolytic cell for the extraction of sodium from sodium chloride
3. Describe and explain the reactions take place at the electrodes.
4. How is metallic sodium usually stored? Explain why it is thus store.
5. Outline the uses of sodium.

---

WEEK:        4 & 5           DAY:                              SUBJECT:

DATE:                            TOPIC:  

SUBTOPIC:                    PERIODS:                      DURATION:

LEARNING OBJECTIVES:       At the end of the lesson, pupils should be able to

1. Give examples of acid and base.
2. List some physical properties of acid and base.
3. State types of acid and base
4. Distinguish between acid and base.
5. Name local materials used in making soap.
6. Identify the active ingredients in the local materials used in making soap.
7. Make soap from local materials.
8. State the uses of soap.
9. Prepare a sample salt with different method

ENTRY BEHAVIOUR/ PREVIOUS KNOWLEDGE: the students are familiar with soap.

KEY VOCABULARY WORDS: substance,   industry, Synthetics.

INSTRUCTIONAL MATERIALS: Whiteboard/Chalkboard , Explanatory posters/pictures rocks,  Explanatory videos on domestic rocks.

CONTENT:

ACIDS, BASES, SALTS

ACIDS AND BASES

An Acid is a chemical substance that can react with other materials. They are used in specific places like laboratory, industry and research centres. Unripe fruits contains acid that is why if you taste an unripe orange it will be sour. Etc.

Types of acids

There are Natural acids and the Synthetics acids.

NATURAL ACIDS

NATURAL ACIDS are called organic acids: this acid occurs naturally, they are found in plants and animals.

EXAMPLES OF NATURAL ACIDS

1. Ascorbic acid, or acetic acid in vinegar
2.  Citric acid in lime.
3. Lactic acid in spoilt milk.
4. Tartaric Acid in grape.

SYNTHETICS ACIDS

Synthetic acids are produced by human – beings (scientists) in the laboratory.

EXAMPLES OF SYNTHETICS ACIDS

1. Hydrochloric acid
2. acetic acid
3. nitric axcid
4.  sulphuric acid
5.  tetraoxosulphate (VI) acid.

PHYSICAL PROPERTIES OF ACIDS

1.  They have sour taste.
2. Concentrated acids can are corrosive.
3. They turn blue litmus paper red.
4. The concentrated acid can react with plastic and metals and damage them.
5. They neutralize bases to form salt and water.

USES OF ACIDS

1. They are used in the manufacture of paint, fertilizers, drugs and other chemicals in dustry.
2. They are used as solvent.
3. They are used in the production of gasses like hydrogen, carbon dioxide.
4. They are used to produce chemicals in the laboratory.

       BASE

Base are chemical substances that react with acid to form salt and water only. They are found in natural objects like wood ash, burnt palm, bunch of waste etc.

                         Types of Bases

The two type of bases are:

1. Soluble bases or alkalis bases: these are bases that are soluble in water. Examples are sodium hydroxide (caustic soda), potassium hydroxide (caustic potash).
2. Insoluble bases: these are bases that are not soluble in water, e.g. copper (II) oxide and Zinc Oxide.

PHYSICAL PROPERTIES OF BASE

1. Base have bitter taste.
2. Base are slippery or soapy to touch.
3. They turn red litmus paper to blue.
4. Concentrated base are corrosive.

              USES OF BASES

1. They are used in the production of soap.
2. They are used in the production of chemicals.
3. Some bases are used in the production of glass, drugs and detergents.
4. They are used in the production of salt when dissolved in acids.
5. Lime water (Calcium hydroxide), which is base is used in the production of plaster of Paris (POP).

INSTRUCTIONAL PROCEDURE

• The Teacher revises the previous lesson (ROCK).
• The Teacher introduces the lesson through question and answer (Acid and Bases).
• The Teacher explains the lessons.
• The Teacher write the note on the board.

There are 3 methods to prepare salts:

1. Precipitation method. – to produce INSOLUBLE salts. – Reagents: (aqueous) + (aqueous) …
2. Excess/ICA method. – to produce SOLUBLE salts. – Reagents: (aqueous; usually an acid) + (solid; excess METAL/ METAL OXIDES/ METAL HYDROXIDES/ METAL CARBONATES) …
3. TITRATION method.

SALTS PREPARATION

There are 3 methods to prepare salts:

1. Precipitation method

– to produce INSOLUBLE salts
– Reagents: (aqueous) + (aqueous)
– Examples: BaSO₄, CaSO₄, AgCl, PbCl₂ etc.

2. Excess/ICA method

– to produce SOLUBLE salts
– Reagents: (aqueous; usually an acid) + (solid; excess METAL/ METAL OXIDES/ METAL HYDROXIDES/ METAL CARBONATES)
– Note: some metals such as Cu/Ag cannot be used as they are unreactive & Group I metals such as Na/K as they are too reactive**
– Examples: CuSO₄, CuCl₂, Ba(NO₃)₂ etc.

3. TITRATION method

– to produce SOLUBLE A1 (Ammonium + Group I) SALTS
– Reagents: (aq; acid) + (aq; base)
– Examples: NaCl, KCl, NH₄NO₃ etc.

TIPS:
– you have to be very familiar with the solubility table; to produce insoluble salts there is only one method – PRECIPITATION.
– However, if the salt you want to produce is soluble, you have to determine if it is an ‘A1’ salt. If it is, use the TITRATION method. If it is not ‘A1’ salt, use the EXCESS method.
– Remember A1 (Ammonium + Grp I) to get your A1 in Chemistry)

LEARNERS ACTIVITIES: Learners participate in the class discussion

LESSON EVALUATION:  Teacher ask the learners to:

• Identify and classify rocks according to colour, hardness, texture.
• List some three important uses of rocks such as construction and beautification.
• Name three major landmark rocks in Nigeria.

CONCLUSION: the teacher summarize the lesson.

WEEK:        6-       CONTINUOUS ASSESSMENTS

MAKING OF SOAP S USING ACTIVE INGREDIENT – SODA SOAP

Active ingredients are the chemical used in soap making. They are classified into two (2).

1. Acids: examples are acetic acid and sometimes sulphuric acids.
2. Bases: soluble base (Alkalis) e.g. caustic soda, caustic potash etc.

Materials needed for soap: stove (any source of heat), frying pan, clean container, open pot, stirrer.

Steps for producing soda soap

The following are steps for producing soda soap.

1. Heating Palm oil in a frying pan until it changes colour.
2. Remove the fried oil from the stove or burner.
3. Measure small amount of caustic soda into it.
4. Heat the mixture of caustic soda and palm oil.
5. Mix the mixture thoroughly using stirrer until the mixture is thicken.
6. Stop heating the mixture and pour the mixture into an empty milk tin.
7. Allow the content in the milk tin to cool and become harden.
8. Allow the mixture to cool and set
9. Remove the soap from the tin and carry out the following test.
10. Your soap is formed.

MAKING OF SOAP FROM LOCAL MATERIALS

1. Take the husk (skin) of unripe plantain and dry it completely for some days.
2. Burn the dry husk until it turns into ashes.
3. Put the ashes in a frying pan and add a measure amount of palm oil
4. Boil the content
5. Stir the content (fried oil and ashes) continuously with a wooden stick.
6. A semi- solid black soap called native soap is formed.

USES OF SOAP

1. Soap is used for bathing
2. Used when moping and scrubbing of the floor.
3. For washing clothes, plates and other plastics materials.
4. Used to remove grease from machine parts in our industries.
5. Used as cleaning agent in industries to clean can, bottles.

JSS3 Second term Lesson Notes. Basic 9 Free Basic Science Plan for Secondary School. Family trait, Acid, bases and salts,Radioactivity.

---

WEEK:        7-       CONTINUOUS ASSESSMENTS MIDTERM BREAK / MID-TERM TEST

WEEK:        8-       CONTINUOUS ASSESSMENTS

WEEK:        9                 DAY:                              SUBJECT:

DATE:                            TOPIC:  

SUBTOPIC:                    PERIODS:                      DURATION:

LEARNING OBJECTIVES:       At the end of the lesson, pupils should be able to

1. Define radioactivity
2. State types of radioactivity elements  
3. State and Explain types of radiation and properties  
4. Explain the properties of types of radiation
5. State types of nuclear reaction and explain
6. Define x-ray and state it uses   

KEY VOCABULARY WORDS:

INSTRUCTIONAL MATERIALS:

CONTENT:

RADIOACTIVITY

Radioactivity is the spontaneous disintegration of the nucleus of an atom of an element. 

Radioactivity involves nucleus reactions. Chemical reaction involves movement of element in its nucleus, the force holding the nucleus become weaker. Such atom becomes unstable, it may break up on its own accord with emission of energy.

    The first scientist to observe spontaneous emission of radiation by uranium salt was Becquerel in 1896. Pierre and Marie Currie also isolated two new radioactive element -1.polonium 2.radium

  Radioactive elements are isotopes of elements  having unstable nucleus that break spontaneously with emission of radiation and release of large amount of energy in achieving a stable composition .isotopes are element with equal nucleus of proton but different numbers of neutron in nucleus . 

 Examples of Radioactive element are carbon 14; uranium -238, cobalt-60,uranium-235, hydrogen-3 radium -241 thorium-232, potassium-40.

 

 TYPES OF RADIATION AND PROPERTIES

ALPHA EMISSION

 1. ALPHA EMISSION –[α]radioactive or radio isotopes emits an alpha particles which is represented [He].The mass number  of the radioactivity isotope is reduced by 4 and the atomic number also reduced by 2

   PROPERTIES OF ALPHA EMISSION 

 1. it is positively charge .              

2. it has penetrating power and can be stopped by sheet of paper .

3. it can be deflected by towards the negatively plate in an electrostatic field since they are positively  

4. it has high ionizing power .

5. it has helium particles.

BETA EMISSION

• BETA EMISSION –[β] when a radioactive isotope element emission beta particle, the atomic number is increased by 1. This does not affect the mass number. Beta particle is represented by i.e. A proton with the loss of an electron with escape of Beta particles.
•  

    PROPERTIES OF BETA EMISSION.

1. The particle is negatively charged.

2. It has a relatively small mass.

3. They are deflected to the positive plate in an electrostatic field.

4. It has more penetrating power than alpha particle.

5. It has lower ionizing power than alpha particle. 

GAMMA (γ) EMISSION

• GAMMA (γ) EMISSION – gamma ray is represented by [γ] it is often emitted along alpha and beta particles.

  PROPERTIES OF GAMMA EMISSION

1. gamma rays are electron magnetic waves similar to visible light

2.it has least ionizing power

3. it has most penetrating power than alpha & beta 

4. it causes fluorescence in sodium iodine and zinc sulphate.

5. it is un affected by electrostatic field .

 TYPES OF NUCLEAR REACTION

1. NUCLEAR FISSION –this is the breaking down or splitting of heavy radioactive isotopes to produce smaller [lighter] isotopes of other element.

2. NUCLEAR FUSION – this is when two or more light nucleus come together to form a heavy nucleus

       X-RAYS

    X-rays are electromagnetic waves. They penetrate through most solid materials . soft x-rays are used in medicine to take photographs of human body parts  it is also used in study the arrangement of particles in crystal .lattice especially protein.

  USES OF RADIOACTIVITY.

1. It is used in generating electricity

2. It is used in curing cancer or cancer treatment

3. In food industry it is used to kill decay causing bacteria and mould

4. It is used as a tracer

5. It is used in carbon dating to determine the age of specimen        

ASSIGNMENT

1. Gamma particles have /are____ A. positively charged  B. deflected by force field  C .most penetrating power

2.Danger of  radioactive ray does not include    A. destruction of body cell  B. undesirable hereditary effects  C. tracer of body effects  D. death due to over exposure.

3. The radiation used to examine soft body tissue is …………. Ray  A. γ    B. β   C. α  D.X

4. Radioactivity is the spontaneous decay of the   A. nucleus   B. atom  C. electron  D. proton

---

WEEK:        10                DAY:                              SUBJECT:

DATE:                            TOPIC:  

SUBTOPIC:                    PERIODS:                      DURATION:

LEARNING OBJECTIVES:       At the end of the lesson, pupils should be able to

1. Description of Ozone Layer.
2. Importance of the Ozone Layer.
3. The hazards of Ozone Layer Depletion to Life.
4. Control Measures against the Depletion of Ozone Layer.
5. Global Warming.
6. Consequences of Global Warming.
7. Control of Global Warming.

KEY VOCABULARY WORDS:

INSTRUCTIONAL MATERIALS:

CONTENT: 

DEPLETION OF OZONE LAYER

DESCRIPTION OF OZONE LAYER 

Ozone is a pale blue poisonous gas found in the earth’s upper atmosphere. Ozone (O₃) is a triatomic molecule of oxygen. It is stable than the diatomic oxygen gas (O₂). It is present in low concentration in the troposphere. Ozone was first discovered by Louis Soret in 1865 and confirmed by Schonbein in 1867.

The amount of Ozone in the atmosphere is measured in Dobson’s unit.

The stratosphere (upper atmosphere) has highest concentration of ozone to form what is called the ozone layer. The ozone layer is about 10km-50km above d earth surface.

Ozone is produced in the atmosphere by the action of ultraviolet ray from the sun on oxygen.

O₂  + UV —-> 2[O]

[O] + O₂ —-> O₃

The ozone is destroyed by free oxygen atoms or elements that react with oxygen.

O₃ + [O] —-> 2O₂

The depletion of ozone layer simply means the continuous reduction in the amount of ozone in the atmosphere. Substances like chlorofluorocarbons (CFC), carbon monoxide (CO), nitrogen oxides etc, are responsible for the depletion of the ozone layer.

IMPORTANCE OF OZONE LAYER

1. Ozone is very important in the preparation of pharmaceuticals and synthetic lubricants.
2. Ozone is used for bleaching substances.
3. Ozone is used to kill microorganisms in water system.
4. Ozone layer protect the earth from the heat of the sun.
5. The ozone layer shields man, animals and plants from the harmful ultraviolet rays from the sun.

INDUSTRIAL USES OF OZONE

Industrially ozone is used to:

1. disinfect laundry in hospitals and food factories.
2. deodorize air and objects especially after fire.
3. assist in processing plastics to allow adhesion of inks.
4. wash fresh fruits and vegetable to kill yeast, mould and bacteria.
5. manufacture chemical compounds.

EVALUATION

1. What is ozone layer?
2. Briefly explain how the ozone layer is formed.
3. What are the importance of the ozone layer.

THE HAZARDS OF DEPLETION OF OZONE LAYER TO LIFE ON LIFE

1. Exposure of the skin of man and other animals to the dangerous ultraviolet rays of the sun which can cause cancer of the skin.
2. Depletion of the ozone layer allows more ultraviolet rays to reach us which may harm aquatic plants and animals thereby disrupting the ecosystem.
3. Ozone layer depletion leads to the increase in the amount of greenhouse gases which  leads to excessive warming of the earth resulting to alteration of season.
4. Depletion of ozone layer leads to global warming which contributes to flooding and other related hazards.
5. Depletion of ozone layer in the lower atmosphere may lead to increase in toxic gases.

CONTROL MEASURES AGAINST DEPLETION OF OZONE

1. There must be regulation on the use of chlorofluorocarbons (CFC).
2. There must be a reduction of bush burning.
3. There must be control of burning in household activities.
4. Elimination of chemicals responsible for the depletion of the ozone layer.
5. Reduction of poisonous gases that can interact negatively with the ozone layer.
6. Development of technology that will not emit dangerous gases from household equipments like refrigerator, air-conditioner etc.

DEPLETION OF OZONE LAYER

Description-Atmosphere is the region of air above  the earth surface. The principal layers of the atmosphere according to temperature of hotness are thermosphere, mesosphere, stratosphere and troposphere. The ozone layer is located in the stratosphere of the atmosphere where it forms a protective layer shielding life on earth from the sun’s harmful ultra-violet radiation. The stratosphere is about 19km to 48km above the earth surface.

Causes of Reduction in Ozone Layer

There are many gases in the atmosphere such as carbon(iv)oxide, water vapour, ozone and methane

When these gases combine with chemical release from refrigerator compressor called  Chlorofluorocarbon(CFC) causes reduction in the ozone layer of the atmosphere.

Importance of ozone layer

-It brings about a cooling effect to the atmosphere and the earth surface

-It absorbs high energy radiation from the sun such as ultra-violet radiation that cause sunburn to  the skin..

Effects of the Depletion of Ozone Layer

-It does damage to human health when the depletion exposes human body to ultra violet light which causes disease such as skin cancer, cataract ,sunburn and weakening of immune system and quick aging.

-It causes retardation in plant growth and development.

-It also poses threat to marine life

-Depletion of ozone layer causes decrease in ozone layer in the stratosphere which makes more ozone to be present in lower atmosphere whose effect result to greenhouse gas. It leads to global warming which in turn lead to melting of polar ice leading to rising in sea level and climatic changes around the world.

Control of ozone Depletion

-Desisting from using pesticides

-Reducing number of vehicles on the road

-By utilizing environmentally friendly cleaning product

-By prohibiting the use of nitrous

-By reducing bush and household burning habits.

ASSIGNMENT

1. Where is the ozone layer located in the atmosphere?  A. earth surface  B.stratosphere  C.mesophere  D. lithosphere

2. Which of the following is not a consequence of the depletion of ozone layer?  A. global warming  B.greenhouse effect  C.ice melting and flooding  D.formation of cloud

3. Which of the following is greenhouse gas?  A Chlorine  B. Water vapour  C.  Oxygen  D. Sulphur

4. Which of the following is not an importance of ozone layer?  A  It purifies the atmosphere of CO₂   B.It releases heat to the earth surface  C.It absorbs high energy radiation from the sun  D.It absorbs water vapour from the earth crust.

6. Which of the following is not a control measure against the depletion of the ozone layer?  A. controlling the use of chlorofluoro-carbons B.constant bush burning  C.regular servicing of automobiles  D.reducing the rate of bush burning

7. The stratosphere is located about………. Above the earth surface   A.32km-40km   B.19km-48km   C.16km-18km  D.6km-12km

8a.State the location of the ozone layer in the atmosphere

b. State three importance of the ozone layer

c. Write three effects or hazards caused the depletion of ozone layer on the environment.  

EVALUATION

1. State five hazards that may result from the depletion of the ozone layer.
2. State five control measures against ozone layer depletion.

GLOBAL WARMING

Global warming is the increase in the average temperature of the earth over a prolonged period of time.

Two of the major causes of global warming are:

1. depletion of the ozone layer
2. green house effect (increase in greenhouse gases).

Greenhouse effect is the reflection of radiant heat back to the earth as a result of accumulation of greenhouse gases (CO_2, H₂O CH₄) in the lower atmosphere. The most important greenhouse gas is CO_2. The increase in the amount of carbon dioxide in the atmosphere is a major cause of greenhouse effect and global warming.

Sources of carbon dioxide in the atmosphere include:

• burning of fossil fuels like coal, petrol, kerosene etc.
• release of carbon dioxide from the exhaust of vehicles.
• release of carbon dioxide from factories.
• increase in the population of man also contributes to the high percentage of carbon dioxide.
• deforestation.
• bush burning.
• urbanization.

CONSEQUENCES OF GLOBAL WARMING

1. Seasonal/climate change.
2. Rising oceans.
3. Increase in flooding occurrences.
4. Melting ice caps or polar ice.
5. Increase in average temperature of the world.

CONTROL OF GLOBAL WARMING

Global warming can be control through the following activities.

1. Planting of trees will purify the atmosphere by absorbing carbon dioxide for photosynthesis and releasing oxygen which contributes to the formation of ozone layer.
2. Reduction in bush and waste burning.
3. Recycling of waste materials.
4. Use of alternative energy sources other than fossil fuels e.g. solar power, wind turbine, water turbine.
5. Electric vehicles should be used to reduce emission of carbon dioxide.

EVALUATION

1. What is global warming?
2. State five sources of carbon dioxide to the atmosphere
3. State five control measures of global warming

GENERAL EVALUATION

1. What is a machine?
2. What are greenhouse gases?
3. State five consequences of global warming.
4. Explain why CFC is dangerous to the atmosphere.
5. How can global warming be controlled.

WEEKEND ASSIGNMENT

1. The major cause of greenhouse effect is the accumulation of  A. Water vapour  B. Carbon dioxide  C. Methane gas  D. Oxygen
2. Which of the following is the chemical symbol of ozone?  A. O₃ B. O₂ C. CO₂  D. H₂O
3. Which of the following is not a consequence of global warming?  A. Seasonal changes  B. Increase heat  C. Crop growth  D. Flooding
4. Which of the following can cause ozone layer depletion?  A. CFC  B. Oxygen  C. Water vapour  D. Carbon dioxide
5. Which if the following activities will help to control global warming?  A. Burning of fuel  B. Afforestation  C. Increasing human population  D. Urbanisation

THEORY

1. List five control measures taken to reduce the depletion of ozone layer.
2. Explain the term “greenhouse effect”.

WEEK:        11-              REVISION

WEEK:        12-              EXAMINATION