1. Lewis Model Shows only the electrons in the outermost level. – Called “Valence Electrons” – Valence Electrons determine how elements react. – Write the symbol with 1 – 8 dots around it.

2. Forming Compounds Balance charges so they zero out. – Add subscripts to make the charges balance OR – Use the criss-cross method Write the elements in the order they appear relative to each other on periodic table. Elements on left (cations) before elements on right (anions). NaCl MgF Al 2 O 3

3. Cl H +1 Cl Mg +2 =HCl =MgCl 2 Cl

4. F Na +1 Cl Ca +2 =NaF =CaCl 2 Cl

5. Cl Na +1 Cl K +1 O Na -2 +1 Na +1 =NaCl =KCl =Na 2 O