CHEM 5.9 Polyatomic Ions

Question 1

What is a polyatomic ion ?

Answer 1

A group of atoms (of different elements) that tend to stay together and carry an overall ionic charge - they are bonded together to form a single ion (package deal).

Question 2

What is a polyatomic compound ?

Answer 2

A compound formed from a metal and a polyatomic ion.

Question 3

Naming polyatomic ions

Answer 3

Metal is first, maintaining the same name (Aluminum –> Aluminum)

Then the polyatomic ion, ending in “ate” (Chlorate –> Chlorate)

Question 4

Writing Formulas

Answer 4

1. Write the symbols of the elements and polyatomic ion with their charges.
2. Criss-cross the charges and place brackets around the polyatomic ion if there is a subscript.
3. Cancel to the lowest ratio if necessary by dividing by the largest common factor between subscripts.

Question 5

Copper (||) sulfate

Answer 5

CuSO4

Question 6

KNO3

Answer 6

Potassium nitrate

Question 7

Magnesium hydroxide

Answer 7

Mg(OH)2

Question 8

Sn3PO4

Answer 8

Tin (|V) phosphate