LIWA

Matter

ICSE Class 6 · Chemistry · Chapter 3

What this chapter covers

Key definitions

Matter is anything that has mass and takes up space.

Volume is the amount of space that a thing takes up.

A solid is a state of matter that has a definite shape and a definite volume.

A liquid is a state of matter that has a definite volume but no definite shape.

A gas is a state of matter that has neither a definite shape nor a definite volume.

Intermolecular space is the empty space between the particles of matter.

Cohesive force is the force of attraction between particles of the same kind of matter.

Brownian movement is the zigzag movement of tiny specks, such as pollen grains in water, caused by moving particles striking them.

Temperature is a measure of how hot or cold something is.

Interconversion of states is the change of a substance from one state of matter into another by heating or cooling it.

Melting is the change of a solid into a liquid on heating.

Boiling is the quick change of a liquid into a gas when it is heated to a fixed temperature.

Key points

Questions answered

What is matter? Give two examples of matter you can find in your kitchen.
Matter is anything that has mass and takes up space. Kitchen examples include rice, milk, a steel plate and cooking gas.
Name the three states of matter. Give one example of each.
Solid, for example salt. Liquid, for example oil. Gas, for example air.
Which state of matter has a definite volume but no definite shape?
A liquid has a definite volume but no definite shape.
Why is it easy to squeeze a gas but not a solid?
The particles of a gas have very large spaces between them, so they can be pushed closer. The particles of a solid are already packed very close, so there is almost no space to squeeze.
What is cohesive force? In which state is it strongest?
Cohesive force is the force of attraction between particles of the same kind of matter. It is strongest in solids.
Name the change of state in each case: (a) wet clothes drying, (b) a naphthalene ball getting smaller, (c) water drops forming on a cold bottle.
(a) Evaporation. (b) Sublimation. (c) Condensation.
Why are small gaps left between the rails of a railway track?
The rails expand on hot days. The gaps give them room to expand, so the track does not bend.
Is the burning of a candle a physical change or a chemical change? Explain.
It is mainly a chemical change, because the burning wax forms new substances that cannot be turned back into wax. The melting of some wax near the flame is a physical change.