The website has the complete lesson note for all the subjects in secondary school but this piece showcases the SS1 Chemistry Lesson Note on Particulate Nature of Matter. You can use the website search button to filter out the subject of interest to you.
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Topic: PARTICULATE NATURE OF MATTER
CONTENTS:
(1) Physical and chemical changes
(2) Elements and their symbols.
(3) Atoms, molecules, atomicity
(4) Dalton’s atomic theory
PERIOD 1: PHYSICAL AND CHEMICAL CHANGES
PHYSICAL CHANGES:
DEFINITION: A Physical change is one which is easily reversed and in which no new substances are formed.
Examples:
- Melting of solids to liquids.
- Freezing of liquids to solids.
- Vaporization of liquids to gases.
- Liquefaction of gases to liquids.
- Sublimation of solids to vapour.
CHEMICAL CHANGE:
DEFINITION: A chemical change is one which is not easily reversed andin which a new substance is formed.
Examples:
- Burning of substances.
- Dissolution of metals and limestone in acids.
- Chemical decomposition – like digestion of food.
- Rusting of iron.
- Charring of sugar.
- Dissolution of metals in acids.
DIFFERENCES BETWEEN PHYSICAL AND CHEMICAL CHANGE
| PHYSICAL CHANGE | CHEMICAL CHANGE |
| Easily reversible | Not easily reversible |
| No new substance is formed | New substance is formed |
| No change is mass. | There is a noticeable change in mass. |
| Not accompanied by heat | usually accompanied by heat change. |
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