Question 2.10: Write formulas for the following compounds: (a) Magnesium fl......

STRATEGY

For transition metal compounds, the charge on the cation is indicated by the Roman numeral in the name. Knowing the number of positive charges, you can then figure out the number of necessary negative charges for the associated anions.

(a)  MgF_{2}  Magnesium (group 2A) forms only 2+ a cation, so there must be two fluoride ions  (F^{-})  to balance the charge.

(b)  SnO_{2}  Tin(IV) has a  +4 charge, so there must be two oxide ions  (O^{2-})  to bal-ance the charge.

(c)  Fe_{2}S_{3}  Iron(III) has a  +3 charge and sulfide ion a  -2 charge  (S^{2-})  so there must be two irons and three sulfurs.