Matter Is Made of Particles (Grade 5): The Tiny Pieces We Cannot See

Why this topic matters

Stir a spoon of sugar into water and it seems to vanish. Did it disappear forever? Taste the water: it is sweet! The sugar is still there. In this lesson you find out why: all matter is made of particles that are far too small to see.

What is matter?

Matter is anything that has mass and takes up space (has volume).

• Has mass: you can weigh it on a scale.
• Takes up space: it fills a place.
• Matter: rocks, water, juice, air, steam, clouds, ice, a balloon, you!
• Not matter: light, sound, music, shadows, feelings. They have no mass and fill no space.

Evidence 1: the vanishing sugar

When sugar dissolves, we cannot see it any more, but three clues show it is still there:

• The water tastes sweet.
• The glass weighs more after the sugar is added.
• If the water evaporates, sugar crystals are left behind.

So the sugar broke into particles too small to see. Invisible particles still have mass: 150 g of water + 10 g of salt = 160 g of salt water.

Evidence 2: air is matter

Blow up a balloon. Something fills it and pushes back when you squeeze it. That something is air. Air takes up space and has mass, so air is matter. We just cannot see its particles.

• Pumping air into a basketball makes it bigger and firmer: more air particles are pushed in and press on the inside.

Evidence 3: smells travel

Someone sprays perfume across the room and soon you smell it. Tiny gas particles of perfume spread through the air all the way to your nose. You smell popcorn from your bedroom for the same reason.

Evidence 4: the vanishing puddle

1. The Sun warms the water in a puddle.
2. The water particles move faster.
3. They escape into the air as a gas (water vapour).
4. The particles are still there, just too small and spread out to see.

This is evaporation, the same step you learned in the water cycle. Wet clothes on a line dry the same way.

Solids, liquids and gases

Ice, liquid water and steam are all water particles. What changes is how close they are and how they move.

• Solid: particles packed tightly; they vibrate in place; a solid keeps its own shape.
• Liquid: particles close together but able to slide past each other; a liquid takes the shape of its container.
• Gas: particles far apart and moving fast; a gas spreads out to fill any space.

Argue like a scientist: CER

A claim–evidence–reasoning (CER) answer has three parts.

• Claim: what you think is true. Matter is made of particles too small to see.
• Evidence: facts and observations. Dissolved sugar still tastes sweet and still has mass. We smell perfume we cannot see. Air fills a balloon.
• Reasoning: why the evidence supports the claim. The matter is still there but we cannot see it, so its pieces must be too tiny to see.

Big idea

All matter is made of particles too small to see. Even when matter seems to disappear, its particles are still there.