Year 5 Science

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Cutting a Cube


Have you ever wondered what would happen if you tried to cut something into smaller and smaller pieces? Could you go on doing this forever? Or is there some ‘smallest’ piece, beyond which you cannot go?

Take a look at the big cube on the right. Let’s imagine it is made from only one elemental material, like aliminium, gold or graphite. Now, imagine using a knife to cut the cube in half along all three directions, so that the big cube becomes eight smaller cubes. Next, you cut each of the small cubes into eight smaller cubes. How many cubes do you have now? If you said 64, you are correct!

How many rounds of cutting can we do? Eventually, we will have to use a different cutting technique, because our knife will be too thick. But, no matter what we do, and no matter what element the cube is made of, we can only perform about 30 rounds of cutting. After that, we will have reached the very smallest piece of the material that still has the properties of that material. This smallest piece is called an atom.

Atoms are extremely small: a human hair has a width of about 100,000 atoms! Not all atoms are the same size. For example, an aluminium atom is larger than a helium atom. But even the largest atoms are far too small to see with your eyes.

What Are Atoms Made Of?

As atoms are so small, you might suppose they are the smallest things in the universe. Not really. An atom is simply the smallest part of a material that retains any property of that material. But atoms themselves are composed of even smaller things!

All atoms, whether helium or aluminium or hydrogen or oxygen, are composed of tiny particles called protons, neutrons and electrons. Protons and neutrons are tightly packed in the centre of the atom, called the nucleus. Electrons are found on the outside of the atom. Protons have positive electric charge (shown by the symbol +), electrons have negative electric charge (-) and neutrons have no charge at all.

Just as the north pole of one magnet repels the north pole of another magnet, positive electric charges repel each other. Negative electric charges also repel each other. But, just as the north pole of one magnet will attract the south pole of another magnet, positive and negative electric charges attract each other.

This activity is adapted from pages 296-297 of What Your Year 5 Child Needs to Know, which can be purchased here. Click below to see the related activities.

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