Compound Naming Study Guide printable pdf download

Nomenclature Study Guide

Ionic compounds exchange electrons between the atoms within them; molecular compounds share electrons

between them.

Ionic Compounds

Positive ions are called cations (+), negative ions are called anions (-).

Monatomic Bonding

1. Example – bond sodium (Na) and Chlorine (Cl)

2. Determine the valence of each of the atoms in the formula. Do this by finding the group number in which

the atom is located (remember to ignore the transition metal block in the middle of the table for this).

a. If the atom falls in groups 1 through 4, its valence is positive (+) and is equal to the group number.

b. If the atom falls in groups 5 through 7, its valence is negative (-) and is equal to eight minus its

group number.

3. Sodium is in group 1, so it has a 1+ valence and is written Na

4. Chlorine is in group 7, so it has a 1- valence (8-7 = 1) and is written Cl

5. After writing the elements and valences, the numbers WITHOUT THEIR SIGNS are “crossed over” to

become subscripts.

6. The result is:

7. Since the 1s are understood, they are not written, so the resulting formula (and final answer) is: NaCl

8. When the valences are multiples of each other, as in boron nitride or carbon dioxide, the subscripts must be

reduced to their simplest form.

9. Naming – to name this compound, simply retain the full name of the metal, and include the non-metals with

an “-ide” ending. See your class notes for a list of the “-ide” converted non-metals.

Polyatomic Bonding

1. Polyatomic bonding is very similar to monatomics, except that a polyatomic ion replaces one or more of the

single elements in the exercise.

2. For example, instead of NaCl, consider Na

-2

3. Sodium metal (Na

) and a sulfate (SO

) polyatomic anion can be easily combined. Notice that the sulfate

ion has a valence of 2-. This ion ALWAYS has this valence. Polyatomic ion valences will always be

provided to you in one way or another – you will never be required to derive them from the

component elements.

-2

4. SO

is a complete ion, so the atoms within it are not reduced or otherwise manipulated. It is treated as a

unit, and the subscripts or atoms within it cannot be changed as a part of the crossover activity.

5. In the case of magnesium hydroxide, Mg(OH)

, there are two hydroxide ions. Notice that the sodium and

hydroxide valences were crossed over, but the hydroxide ion itself remains unchanged.

6. Since there are 2 hydroxide ions (the two -1 charges are required to balance the 2+ of carbon), the ENTIRE

ION is included twice and given a subscript of 2. The hydroxide ion is enclosed in parentheses to show

that it is its own unit and is not manipulated – this is true for ANY polyatoimic ion.

Compound Naming Study Guide