BINARY A COMPOUNDS

Classification:

Binary A compounds are two element compounds composed of a Group A Metal chemically bound to a nonmetal.

Naming Rule:

Take the English name of the metal followed by the nonmetal stem plus the ide ending.

Formula Rule:

Form an ion from each constituent (first a metal ion, then a nonmetal ion) and put them together in such number that their charges add up to zero.

Examples

Answer:

a) is named calcium bromide

b) is named boron nitride

c) is named potassium sulfide

d) is not a binary I compound.

Let us derive the chemical formula for:

e) magnesium fluoride

Answer:

e) is the formula for magnesium fluoride.

Common Nonmetal Stems

nonmetal atom    stem    
    carbon       carb-     
    nitrogen     nitr-     
    phosphorus   phosph- 
    arsenic      arsen-     
    oxygen       ox-     
    sulfur       sulf-     
    selenium     selen-     
    fluorine     fluor-     
    chlorine     chlor-     
    bromine      brom-     
    iodine       iod-     

Definitions

Group A metals are those metal atoms belonging to groups IA, IIA, and IIIA in the periodic table. Note that only some of the elements in Group IIIA are metals.

Nonmetals are those atoms that stair-step down the Group A elements begining with boron and ending with antimony.

More Information on Examples

We know this is binary I compound because Ca is a group IIA metal and Br is a nonmetal.

The english name of the metal is calcium and the nonmetal stem is brom.

Thus the name of the compound is: calcium brom + ide.

b) is named boron nitride

We know this is binary I compound because B is a group IIIA metal and N is a nonmetal.

The english name of the metal is boron and the nonmetal stem is nitr.

Thus the name of the compound is: boron nitr + ide.

c) is named potassium sulfide

We know this is binary I compound because K is a group IA metal and S is a nonmetal.

The english name of the metal is potassium and the nonmetal stem is sulf.

Thus the name of the compound is: potassium sulf + ide.

d) is not a binary I compound.

This is not a binary I compound because Fe is a group VIIIB metal.

e) is the formula for magnesium fluoride.

Magnesium is a group IIA metal possessing 2 valence electrons. This element becomes isoelectronic with a noble gas by losing 2 valence electrons forming magnesium ion.





Fluorine is a group VIIA nonmetal which achieves a noble gas configuration by gaining 1 valence electron, thus forming the fluorine ion.





Electrically, these two ions attract one another in such a number that the total charge of the compound formed adds up to zero. Total charge is determined by addition of the superscripted charges of all atoms present in the compound.