Ch26 - Periodic Table + chemical formulas

• Group 1 - Alkali metals

  Group 2 - Alkaline Earth metals

  Group 3 - referred to as the 'topmost element' group

  Group 7 - Halogens

  Group 8 - Noble gases (inert gases)
• Atomic number - number of protons in the nucleus of an atom.

  Mass number - protons + neutrons

  Proton amount must be the same as electron amount.