periodic table

• group 1 - alkali metals
• group 2 - alkali earth metals
• group 17 - halogens
• group 18 - noble gasses
• valency

  group 1 - 1

  group 2 - 2

  group 13 - 3

  group 14 - 4

  group 15 - 3

  group 16 - 2

  group 17 - 1

  group 18 - 0
• group 2 - 13 are transition metals
• diatomic molecules

  F

  H

  O

  Cl

  Br

  Ts

  N

  I

  At