How to read the Periodic Table
# of Protons = Atomic #
# of Electrons (neutral) = Atomic #
# of Neutrons = Atomic mass – Atomic #
Metals – Left side of the Periodic Table (except for Hydrogen)
Nonmetals – Right side of the Periodic Table
Metalloids – 6 that border the zigzag. (B, Si, Ge, As, Sb, Te.)
Periods – Rows on the Periodic Table
 Organized by atomic mass
 There is a gradual change of physical and chemical characteristics as you move
across a period.
 period # indicates the # of electron shells possessed by each element in that
period
Groups or Families – Columns on the Periodic Table.
 Organized by similar chemical and physical characteristics.

# of valence electrons (electrons in outer shell)
(this range of groups have 1-2 valence electrons)
rule of 8: atoms will combine so that their combined total of valence electrons = 8
(so that they have a full outer shell
examples: Na (group 1) has 1 valence electron. Cl (group 7) has 7 valence electrons.
1 = 7 = 8, so Na + Cl = NaCl (sodium chloride – table salt)
Bohr Diagram – shows all shells with electrons and protons
and neutrons in nucleus.
Bohr Diagram for Carbon
Lewis Dot Structure – only shows outer shell and valence
electrons. (electrons placed in pairs around four sides of
element symbol.)