GCSE Chemistry Fundamentals
Atoms are the basic building blocks of everything, made up of protons (+1 charge), neutrons (no charge) in the nucleus, and electrons (-1 charge) orbiting around. Since atoms have equal numbers of protons and electrons, they're electrically neutral.
Compounds form when different atoms bond together chemically, whilst mixtures are just substances mixed together without chemical bonding. You can separate mixtures using techniques like chromatography (where substances travel up paper at different rates), filtration (removing insoluble particles), and distillation (separating liquids by heating and cooling).
Ions are atoms that have gained or lost electrons, giving them a charge. When writing chemical equations, remember that atoms are never created or destroyed - you can only balance equations by changing the numbers in front of formulas.
Key Tip: The periodic table groups elements with similar properties together, making it easier to predict how they'll behave in reactions.