1.  What is the formula for magnesium chloride? Review of Formula Writing…

2.  A positively charged ion is called a cation.  A negatively charged atom is called an anion.  So in an iconic compound the metal is the cation and the non-metal is the anion.

3.  Some metals form more than one type of ion [can have more than 1 type of charge]  We show the charge with a Roman numeral in brackets:  Cu + … copper (I)  Cu 2+ … copper (II)

4.  What is the name for Fe 2 O 3 ?

5. Naming Multivalent Metals  What is the name for Fe 2 O 3 ?  Net charge has to be zero so…  O 2- x 3 = -6  Fe ?+ X 2 = + 6  6/2 = 3 …so the charge on Fe is 3+ Answer: iron (III) oxide

6. What is the formula for chromium (III) oxide ?  Cr 3+ Cl -  Cr +3 x 1 = +3  Cr -1 x 3 = -3Net Charge = 0  Final Answer = CrCl3