States of Matter and Chemical Bonding

Solids, liquids, and gases behave differently because their particles are arranged in unique ways. In solids, particles vibrate in fixed positions like people stuck in their seats, whilst liquid particles slip and slide freely past each other. Gas particles zoom about randomly with loads of space between them.

When substances change state, energy transfers between the material and its surroundings. Melting and boiling need energy input, but freezing and condensation release energy back out.

Elements form compounds by sharing, gaining, or losing electrons to become more stable. Think of Group 1 metals hooking up with Group 7 halogens - the metal loses an electron whilst the halogen gains one, creating a perfect match.

There are three main types of chemical bonds: ionic $between metals and non-metals$, covalent $between non-metals sharing electrons$, and metallic (in pure metals and alloys). Each type creates materials with completely different properties.

Key Point: The particle model helps explain behaviour, but remember - real atoms aren't solid spheres and have forces between them!