Lesson Notes By Weeks and Term - Senior Secondary 1

Term: 1^st Term

Week: 8

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:       

Subject:      Chemistry

Topic:-       Particulate nature of matter I

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

1. Explain physical and chemical changes
2. Define atoms and molecules
3. State Dalton’s law of atomic theory

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION	TEACHER’S ACTIVITY	STUDENT’S ACTIVITY
STEP 1 INTRODUCTION	The teacher reviews the previous lesson on Separation techniques for mixtures	Students pay attention
STEP 2 EXPLANATION	He explains physical and chemical changes. He further defines atoms and molecules	Students pay attention and participates
STEP 3 DEMONSTRATION	He states and explains Dalton’s law of atomic theory	Students pay attention and participate
STEP 4 NOTE TAKING	The teacher writes a summarized note on the board	The students copy the note in their books

 

NOTE

PARTICULATE NATURE OF MATTER

MATTER is anything that has mass and occupies a space Changes occur within and without the matter as a result of the conditions they undergo. These changes are classified as physical and chemical changes

1. Physical changes are changes which are easily reversible and do not produce new ones e.g melting of ice, dissolving ordinary salt or sugar in water and then boiling off the water completely in the presence of heat, magnetization of magnetic materials, etc.
2. Chemical changes are changes in which the change is permanent in nature. New substances are formed e.g burning of wood, rusting of iron, boiling of egg, etc.

 

DIFFERENCES BETWEEN PHYSICAL AND CHEMICAL CHANGES

S/No	Physical change	Chemical change
1.	It is reversible	It is not easily reversible
2.	No new substance is formed	New substance is formed
3.	Minimal heat is sometimes involved	Great amount of heat is involved
4.	Mass remains constant	There is change in mass

 

CONCEPT OF ATOMS, MOLECULES, AND IONS

Matter is made up of discrete particles called atoms, ions, molecules, elements, compounds.

1. Atoms: An atom is the smallest part of an element that can take part in a chemical reaction
2. Element: It is a substance which cannot be separated by any physical means
3. Molecule: Is the smallest part of any substance that is capable of independent existence.
4. Ion: are charged atom, molecule, and compound
5. Compound: is the combination of two or more elements chemically joined together
6. Mixture is the combination of two or more elements physically joined together

Molecules

A molecule is the smallest particle of a substance that can normally exist alone and still retain the chemical properties of that substance, be it an element or a compound.

Molecules may be made up of atoms of the same element or of different elements.

Atomicity is defined as the number of atoms in each molecule of an element.

 

Atomicity	Elements	Formula of molecule (e.g)
Monoatomic	All noble gases and metals	He, Ne, Ar, Kr
Diatomic	Hydrogen, Nitrogen, Fluorine,	H2, N2, O2 etc
	Oxygen, Iodine, Chlorine,
	Bromine
Triatomic	Oxygen as Ozone	O3
Tetra-atomic	Phosphorus	P4
Poly atomic	Sulphur	S8

A molecule of a compound may be small or large. Eg. A hydrogen chloride molecule contains only two atoms, while a starch molecule contains thousands of atoms.

 

Ions

An ion is an atom or group of atoms which possess an electric charge. There are two types of ions

1. Cation; positively charged ions. Generally, metals form cations. These are formed by loss of electrons e.g Ca²⁺, Na⁺, Fe³⁺
2. Anions; negatively charged ions. Generally, non-metals form anions. These are formed by gain of electrons e.g Cl^-, O^2-

 

DALTONS ATOMIC THEORY

1. All matter are made up of tiny indivisible particle called atoms.
2. Atom can neither be created nor destroyed.
3. Atoms of the same element have the same properties and the same mass
4. Atoms of different element have different mass and different properties.
5. When atoms combine with each other they do so in simple whole number ratio.

 

EVALUATION:    1. Define matter

2. List and explain the types of changes, giving two examples of each

3. Write short notes on

2. atoms
3. molecules
4. ions

4. State Dalton’s law of atomic theory

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively