Atomic Structure, Bonding & Chemical Changes
Ever wondered why some materials conduct electricity whilst others don't? It all comes down to atomic structure and how atoms bond together. You'll master these concepts faster than you think!
Compounds form when two or more elements chemically bond together, whilst mixtures are just elements hanging out together without any chemical bonding. Think of compounds like a married couple (permanently joined) and mixtures like flatmates (living together but separate).
There are three main types of bonding you need to know. Metallic bonding occurs between metals with delocalised electrons that can move freely - this is why metals conduct electricity. Ionic bonding happens between metals and non-metals through charge transfer, creating strong electrostatic attractions. Covalent bonding involves sharing pairs of electrons between non-metals.
Key Insight: The type of bonding determines the properties! Ionic compounds have high melting points due to strong lattice structures, whilst simple covalent compounds have low melting points because of weak intermolecular forces.
Historical atomic models evolved from Thomson's plum pudding model (electrons embedded in positive charge) to Bohr's shell model, and finally to our current understanding of atoms being mostly empty space with a positive nucleus and electrons orbiting outside. Metal reactivity depends on how easily atoms form positive ions - the further down Group 1 you go, the more reactive metals become because electrons are further from the positive nucleus.
