Atoms and bonding

Chemistry makes more sense once you can read what a formula is telling you and why atoms join the way they do. This topic covers that groundwork. You start with periodic table trends: how atomic radius, electronegativity and reactivity change across a period and down a group. Most slips come from memorising a trend backwards rather than reasoning from the number of shells and the pull of the nucleus. Next is the difference between ionic and covalent bonds. Metals with non-metals usually transfer electrons, while non-metals with each other share them. The final page is counting atoms in a formula, which sounds basic but trips up many students when brackets and coefficients appear together. A subscript counts only the atom it follows, a bracket multiplies everything inside it, and a coefficient multiplies the whole formula. Get this page right and balancing equations in the next topic becomes far easier. Try each practice set before moving on, and say why each answer works.