Polyatomic and Multi-Valent Ionic Compounds

Question 1

What are multi-charged/multi-valent ionic compounds?

Answer 1

Some metals, found in the middle of the periodic table are able to form more than one kind of ions. To distinguish between the different ions, we write a roman numeral in brackets after the name of the metal in the compound to indicate its ionic charge.

• Multi-charged ions are always metal.
• Most often, these multi-charged or multi-valent elements are found in the “transition metals” portion of the periodic table.
• The most common charge is is listed first on the periodic table.
• In order to name just the multi-charged ion you must use roman numerals to indicate the charge of the ion..

Question 2

How do you write the chemical formula for a multi-charged ionic compound?

Answer 2

1. Determine the charge of each ion(Since the first ion has the roman numeral you will know its charge without having to go to the periodic table).
2. Balance the charges by adding subscripts to the formula.

Question 3

How do you write the name of multi-charged ionic compounds based o the chemical formula?

Answer 3

1. Write the name of the first ion in the chemical formula.
2. Add roman numerals for the charge of the metal.
3. Write the name of the second ion(the non-metal) with the -ide ending.

Question 4

What are complex/polyatomic ions?

Answer 4

A cluster of atoms that behave as a single unit in a chemical compound. These complex/polyatomic ions are found in the table at the top of your periodic table. Since complex/polyatomic ions are charged, they have the ability to form compounds with simple ions or with other complex/polyatomic ions.

Question 5

How do you write the chemical formula of a complex/polyatomic ion?

Answer 5

1. Treat the polyatomic ion as one unit and find its charge in the polyatomic ions table.
2. Determine the charges for the metal ion and the polyatomic ion.
3. Balance the charges using subscripts(you must use brackets around the polyatomic ion if there is more than one).

Question 6

How do you write the name of complex/polyatomic ionic compounds?

Answer 6

1. Write the name of the cation first.

2. Write the name of the anion second(do not change the ending of the anion to -ide).