1. Converting Ionic Names to Formulas

2. Ionic Compounds
Ionic compounds are formed when positive and negative ions are attracted to each other.
Ionic compounds have a net charge of 0.

3. Formation of Ionic Compounds
Ions form compounds with no charge.
Example: H+ and S-2
S-2 has a negative two charge.
Needs 2 H+ to have no charge.
Formula = H2S
Example: Al+3 and O-2
The only way to even out the charges is two Al+3 ions for ever three O-2.
Formula: Al2O3

4. SHORTCUT Charge-Swapping Determine the charge of each ion.
The charge becomes the subscript of the other ion

5. Example Problems Beryllium fluoride Magnesium phosphide
Be+2 + F-1 = BeF2
Magnesium phosphide
Mg+2 + P-3 = Mg3P2

6. Stock System of Naming Some metals have more than one charge.
Examples:
Mercury can have a charge of +1 or +4
Iron can have a charge of +2 or +3
In ionic naming, these metals have a Roman numeral after their name to tell the positive charge.

7. Roman Numerals One = I Two = II Three = III Four = IV Five = V
Six = VI
Seven = VII
Eight = VIII
Nine = IX
Ten = X

8. Advanced Formula Practice
Manganese (II) iodide
The charge is +2 on the manganese (Mn+2)
Iodide = iodine with a -1 charge. (I-1)
Mn+2I-1 (Cross charges to get the subscripts)
MnI2

9. Advanced Formula Practice
Mercury (IV) silicide
Mercury has a charge of +4 (Hg+4)
Silicide = silicon with a charge of -4 (Si-4)
Hg+4Si-4 (Since the charges are the same number, you can just write the symbols together)
HgSi