Formula Writing notes:
1. represent each kind of
element in a compound with the correct symbol for that element
2. use subscripts to
indicate the number of atoms of each element
of the compound. If one atom is present,
no subscript is used
3. write the symbol for the element with the lower
electronegativity first, then the element with the higher electronegativity.
This is the same as the + ion first, the – ion second.
Criss cross method:
an oxidation number (What ion will the element make when it completes it's
the oxidation #
3 elements (look at Table E for the Polyatomic Ion)
the metal keeps it's name, change the last element to -IDE
EX: sodium + chlorine
An element combined with a polyatomic ion found on Table E Everyone
keeps their name
Calcium + Carbonate
· Used when a metal has more than one oxidation state
.Oxidation state used will be in Roman numerals in parenthesis.
EX: iron (III) oxide
Fe+3 O-2 = Fe2O3