3.2Bonding: the structure of matter

1.1  Bonding: the structure of matter

Element: a substance that cannot be split into anything simpler, in a chemical reaction. Each element has a unique proton number.

Mixture: two or more elements mixed together BUT that are not chemically combined Compound: a substance in which two or more different elements are chemically combined. Metals:

  1. strong
  2. malleable and ductile
  3. sonorous
  4. good conductors of heat and electricity
  5. have high melting and boiling points (except mercury)
  6. high density
  7. react with oxygen to form (usually) basic compounds called metal oxides (aluminium oxide is amphoteric)
  8. in reactions they form positive ions (cations)
  9. some, g. iron, are magnetic.

Non metals:

  1. Are brittle
  2. Have lower melting and boiling points than metals
  3. Poor conductors of electricity, except for graphite (carbon) and are also bad conductors of heat
  4. Have low densities
  5. Most react with oxygen to form (usually) acidic oxides (carbon monoxide is neutral)
  6. Form negatively charged ions (anions) in a chemical reaction

Alloy: a mixture where at least one other substance is added to a metal, to improve its properties; the other substance is often a metal too (but not always) e.g. brass (70% copper and 30% zinc) is harder than copper, does not corrode, used in musical instruments.