This article on states of matter for kids explains matter, its definition, the three states of matter and gives an example of state changes with water. Learn more about matter for kids with this easy to understand article.

## Definition of matter for kids

Matter is anything that takes up space and has mass. It can be a living thing or a non-living thing.

Examples of matter would be table, honey and oxygen.

### What is mass

Mass is the amount of matter in an object.

The units of measurement for mass are kilograms or grams. You can measure your mass using a weighing machine.

Mass is not weight.

The difference between the weight of an object and the mass of an object is that mass is the amount of matter an object has while weight is the amount of force on an object due to gravity.

### What is volume

Volume is the amount of space occupied by a matter. For liquids, volume can be measured using a measuring cylinder. For solids, you can measure volume by putting it in a predetermined amount of water in a measuring beaker and looking at the difference in volume before and after the solid is placed into the water.

The units of measurement for volume are cubic centimeters, cubic meters, liters and milliliters.

### What is not matter

Things that are not matter do not take up space and do not have mass.

They are also called ‘non-matter’.

Examples of non-matter would be light, heat and shadow.

## States of matter for kids

Matter can exist in three states:

1. Solid
2. Liquid
3. Gas

### Properties of matter for kids - Solids

Solids have a definite shape and a definite volume. This means that their shape and volume is fixed.

The volume of a solid is measure in cubic meters or cubic centimeters.

Credit: By Kayau (Own work) [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

Solids have particles that are in fixed positions and packed closely together due to very strong forces. The particles in a solid vibrate about in their fixed positions.

Examples of solids would be ice, plasticine, computer and pencil.

Solids cannot be compressed. This means that even if you apply force to a solid, you cannot make it less or make it fit into a smaller space.

Why Plasticine is a Solid

Plasticine is a solid as even though its shape can be changed, the change only happens when force is applied to it unlike liquids and gases. Plasticine also has a definite shape and a definite volume like all other solids.

### Properties of matter for kids - Liquids

Liquids have a definite volume, but they do not have a definite shape. This means that they will take the shape of a container they are placed in.

Liquid have particles that do not have fixed positions and they can move around as they are packed less closely to each other as the forces between them are weaker than the ones in a solid. The particles also vibrate even though they can move around freely.

Examples of liquids would be water, juice and syrup.

Liquids also cannot be compressed.

### Properties of matter for kids - Gases

Gases have no definite volume and no definite shape. They can be felt but cannot be seen. They also take up the shape of the container (for example, a balloon) but it's just that you cannot see them.

Gases have particles that are far apart from one another as there are very weak forces pulling them together. Similar to liquids, these particles are able to move around freely. However, they move at even higher high speeds and they can occupy any available space.

Examples of gases would be carbon dioxide, water vapor and steam.

Gases can be compressed which means you can squeeze them into smaller spaces and change their amounts.

## Changes in states of matter for kids

Changes in states of matter can occur when heat is gained or lost.

• Heat gain can cause matter to change from solid to liquid
• Heat gain can also cause matter to change from liquid to gas
• Heat loss can cause matter to change from gas to liquid
• Heat loss can also cause matter to change from liquid to solid

### Example of change in states of matter - water

A good example of changes in state is water because it can change from one state to another and they can exist in all three of these states. As a solid, it is called ice. As a liquid, it is simply water. As a gas, it can exist as water vapor or steam.

Evaporation causes water to change into water vapor at any temperature through heat gain. This means that the state of water changes from liquid to gas. In the process of evaporation, the particles in a liquid gain energy and vibrate even quickly until the forces holding the particles together become very weak. Then, these particles move further apart, and the liquid changes into a gas.

Freezing causes water to change into ice when it is 0 through heat loss. This means that the state of water changes from liquid to solid. In the process of freezing, the forces holding the particles together become stronger and bring them together into a fixed position, causing them to change into a solid.

Melting causes ice to change into water when it is 0 through heat gain. This means that the state of water changes from solid to liquid. In the process of melting, the forces holding the particles together become weaker and the particles separate, causing them to change into a liquid.

Condensation causes water vapor or steam to change into water at any temperature through heat loss. This means that the state of water changes from gas to liquid. In the process of condensation, the forces holding the particles together become stronger and bring them together to form small groups, causing them to change into a liquid.

Boiling causes water to change into steam when it is at 100 degrees celsius through heat gain. This means that the state of water changes from liquid to gas. In the process of evaporation, the particles in a liquid gain energy and vibrate even quickly until the forces holding the particles together become very weak. Then, these particles move further apart, and the liquid changes into a gas.

The difference between water vapor and steam is that steam is actually water vapor, except that steam is hot water vapor at 100 degrees celsius.