Matter and Its States
Subject: Science (Chemistry) | Topic: Matter and Its States
For TLT, ECT, PST, JEST & All Competitive Exams
So far we have explored the human body and how its systems work together. Now we turn to Chemistry, starting with the most basic idea of all: everything around us — the air we breathe, the water we drink, the chair we sit on — is made of matter. This topic is a foundation for all future chemistry topics and is frequently tested in ECT, BPS-15, PST, JEST, and other competitive exams.
What is Matter?
Matter is anything that has mass and occupies space (has volume). Everything in the universe that you can touch, weigh, or see taking up space is made of matter — including solids, liquids, and gases. Even air, though invisible, is matter because it has mass and fills space.
The Three States of Matter
Matter exists in three common physical states: solid, liquid, and gas. The state a substance is in depends on how closely its particles are packed and how much energy those particles have.
Particle Arrangement in the Three States
1. Solids
In a solid, particles are packed tightly together in a fixed, orderly arrangement. They can only vibrate in place, not move around freely. As a result, solids have a fixed shape and a fixed volume, such as ice, wood, or a stone.
2. Liquids
In a liquid, particles are close together but can move and slide past one another. Liquids have a fixed volume but no fixed shape — they take the shape of whatever container they are poured into, such as water or milk.
3. Gases
In a gas, particles are spread far apart and move freely and rapidly in all directions. Gases have no fixed shape and no fixed volume — they expand to fill whatever container or space they are in, such as air or oxygen.
Properties of the Three States
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Fixed | Not fixed (takes shape of container) | Not fixed (fills the container) |
| Volume | Fixed | Fixed | Not fixed |
| Particle Arrangement | Tightly packed | Close, but can move | Widely spaced |
| Compressibility | Cannot be compressed | Very difficult to compress | Can be compressed easily |
Changes of State
Matter can change from one state to another when heat energy is added or removed. These are called physical changes, since no new substance is formed — only the arrangement and energy of the particles change.
- Melting — Solid changes to liquid by gaining heat (e.g., ice melting into water).
- Freezing — Liquid changes to solid by losing heat (e.g., water freezing into ice).
- Evaporation/Boiling — Liquid changes to gas by gaining heat (e.g., water boiling into steam).
- Condensation — Gas changes to liquid by losing heat (e.g., steam turning back into water droplets).
- Sublimation — Solid changes directly to gas without becoming liquid (e.g., dry ice, or naphthalene balls turning into vapor).
Why This Topic Matters
Understanding matter and its states is the foundation for all of chemistry. It explains everyday phenomena like why ice melts in your hand, why water boils when heated, and why a helium balloon expands or shrinks with temperature. This topic also sets the stage for future chemistry topics such as elements, compounds and mixtures, and physical and chemical changes, all of which build on the basic idea that matter is made of tiny particles in constant motion.
Practice MCQs
1. What is matter?
a) Anything with mass and volume b) Only solids c) Light and heat d) Only liquids
2. Which state of matter has a fixed shape and fixed volume?
a) Gas b) Liquid c) Solid d) Plasma
3. What is it called when a solid changes directly into a gas without becoming liquid?
a) Melting b) Condensation c) Sublimation d) Freezing
4. In which state of matter are particles spread far apart and move freely?
a) Solid b) Liquid c) Gas d) None of these
5. What is the process called when a liquid changes into a solid?
a) Melting b) Freezing c) Boiling d) Evaporation
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