Chapter 11 Chemical Bonds: The Formation of Compounds from ...

11.4 Predicting formulas of ionic
compounds
the concept forms the basis for our understanding
of chemical bonding:
in almost all stable chemical compounds of
representative elements, each atom attains a noble
gas electron configuration
predicting the formulas of ionic compounds
ex. Compound formed between Ba and S
Ba [Xe]6s 2
S [Ne]3s 2 3p 4
loses 2 electrons to achieve
Xe configuration Ba 2+
gains 2 electrons to achieve
Ar configuration S 2-
BaS
ex. 11.8 predict formulas for
(a) magnesium sulfide Mg 2+ S 2- MgS
(b) potassium phosphide K + P 3- K10
3 P
(c) magnesium selenide Mg 2+ Se 2- MgSe