Everyday Reactions

4. A cluster of atoms that make up an element or a compound.
8. An exothermic chemical reaction that takes place in the cells of living things. It is the reaction between sugar and oxygen to produce carbon dioxide and water. The energy produced by the reaction is used by the organism to live, move and grow.
9. The number of protons and neutrons in an atom.
10. A chemical reaction that absorbs energy.
12. A chemical reaction that releases energy.
13. Chemicals produced in the chemical reaction; they are written on the right-hand side of the arrow.
15. A pure substance that is made up of two or more different types of atoms chemically joined.
16. A cluster of neutrons and protons at the centre of an atom.
17. A small, negatively charged particle; clouds of electrons surround the nucleus of an atom.
18. A particle with no electric charge; it is found in the nucleus of an atom.

1. The fundamental building block of all materials; it consists of a cluster of protons and neutrons surrounded by a cloud of electrons.
2. Chemicals that take part in a chemical reaction; they are written on the left-hand side of the arrow
3. Atoms that have the same number of protons but a different number of neutrons
5. A substance made up of only one type of atom.
6. A positively charged particle found in the nucleus of an atom.
7. The number of protons in a nucleus; the atomic number determines what type of atoms it is.
11. An atom that has gained or lost an electron.
14. A chemical reaction in which a substance burns in oxygen gas to produce light and heat.