1st Term week 3 Lesson Note: Nature of Matter for SS1

 

Class: Senior Secondary School 1 (SSS 1)

Subject: Chemistry
Topic: Nature of Matter
Sub-Topics: States of Matter, Properties of Matter, and Changes of State
Duration: 40 Minutes

1. Definition of Matter

Matter is defined as anything that has mass and occupies space. Everything around us—the air we breathe, the water we drink, the soil, and the books we read—is composed of matter.

According to the Kinetic Theory of Matter, all matter is made up of tiny, discrete particles (atoms, molecules, or ions) that are constantly in motion.

2. The Three States of Matter

Matter exists in three primary physical states: Solid, Liquid, and Gas. Their characteristics depend entirely on how closely packed the particles are and how freely they can move.

Solid State

• Particle Arrangement: Particles are tightly and regularly packed together in a fixed pattern.

• Forces of Attraction: Very strong forces of attraction hold the particles together.

• Movement: Particles cannot move freely; they can only vibrate and rotate about their fixed positions.

• Shape & Volume: Solids have a definite shape and a definite volume. They cannot be easily compressed.

• Examples: Iron rods, wood, stone, glass, and copper sulfate crystals.

Liquid State

• Particle Arrangement: Particles are close together but arranged randomly. There are small spaces between them.

• Forces of Attraction: The forces of attraction are weaker than those in solids, allowing particles to slide past one another.

• Movement: Particles move translationally, colliding with each other and the walls of the container.

• Shape & Volume: Liquids have a definite volume but no definite shape (they take the shape of the container they occupy).

• Examples: Water, ethanol, kerosene, and mercury.

Gaseous State

• Particle Arrangement: Particles are very far apart from one another with completely random arrangements.

• Forces of Attraction: The forces of attraction are negligible (almost non-existent).

• Movement: Particles move at very high speeds in all directions, colliding constantly.

• Shape & Volume: Gases have no definite shape and no definite volume. They expand to completely fill any container and are highly compressible.

• Examples: Oxygen, nitrogen, carbon dioxide, and water vapor.

3. Comparison Table of the States of Matter

Property	Solid	Liquid	Gas
Shape	Definite	Takes the shape of the container	Takes the shape of the container
Volume	Definite	Definite	Indefinite (fills the container)
Compressibility	Incompressible	Practically incompressible	Highly compressible
Particle Motion	Vibration in a fixed position	Slide over one another	Rapid, random motion
Intermolecular Forces	Very strong	Moderately strong	Very weak / Negligible

4. Properties of Matter

The properties of matter can be broadly classified into two categories: Physical Properties and Chemical Properties.

A. Physical Properties

These are properties that can be observed or measured without changing the chemical identity or composition of the substance.

• Examples: Color, odor, taste, melting point, boiling point, density, hardness, and electrical conductivity.

B. Chemical Properties

These are properties that describe how a substance interacts or reacts with other substances to form entirely new products.

• Examples: Flammability, rusting of iron, acidity, reactivity with water or air, and decomposition by heat.

5. Changes of State

When energy (heat) is added to or removed from matter, it can change from one physical state to another. These are physical changes because no new chemical substance is formed.

                  +---------- Melting --------->
                  <-------- Freezing ----------
      [ SOLID ]                                   [ LIQUID ]
          |       +--------- Sublimation ------->     |
          |       <-------- Deposition ----------     |
          |                                           |
          +----------------- Boiling / Evaporation --->
          <----------------- Condensation ------------+
                                  [ GAS ]

• Melting: The process where a solid changes into a liquid upon heating (e.g., ice turning to water).

• Freezing (Solidification): The process where a liquid changes into a solid upon cooling (e.g., water turning to ice).

• Boiling / Evaporation: The process where a liquid changes into a gas. Boiling happens at a specific temperature throughout the liquid, while evaporation happens at any temperature only at the surface.

• Condensation: The process where a gas turns into a liquid when cooled (e.g., water vapor forming dew).

• Sublimation: A direct change from a solid to a gas without passing through the liquid state (e.g., heating iodine crystals, camphor, or ammonium chloride).

• Deposition: A direct change from a gas into a solid without becoming a liquid first (e.g., frost formation).

Evaluation Exercises (For Classwork/Assignment)

1. State the main postulates of the Kinetic Theory of Matter.

2. Using particle arrangement and forces of attraction, explain why gases can be compressed while solids cannot.

3. Classify each of the following as either a physical property or a chemical property:

   • a) Magnetism

   • b) Flammability of cooking gas

   • c) Boiling point of ethanol

   • d) Rusting of an iron nail

4. Define the term Sublimation and give two examples of substances that can sublime.