How to do Ionic Formulas to Names

							         How to do Ionic Formulas to Names

This set of instructions will take in the reverse path of names to formulas. I

believe that once a student understands one direction the instruction to go

the other way is easier. However, we will walk through with more detail

than is needed in the event you are starting with this method first. You will

need you periodic table to perform this activity.

These practice problems are for your use. I encourage you to use all of the

steps outlined until you feel very comfortable in the process. An “ide”

ending means there are only two different atoms present in the compound.

The “ide” ending will modify the name of the compound so you need to

change the name for an element so that it sound familiar, it is OK to guess

at this part as there are not rules to follow.


                       Convert MgCl2 to a name

   1. Look at the back of the periodic table. In the upper right corner is a

      box with the name formula to name. The first question is “Is the

      compound ionic? “

   2. The answer is yes it is made of a metal and non-metal.

   3. Next question is does the cation (the first element in the formula)

      have more than one oxidation number.
4. Look on the front of the periodic table and you will see that

   magnesium is in the second column on the left and they all have only

   one number and that is a 2.

5. Now you write the full name of the cation and if there are only two

   different atoms present, write the anion with an ending of “ide”.

                     Magnesium Chloride


                   Convert Fe2O3 to a name

1. Again, the first question is the compound ionic.

2. The answer is yes, as it is made up of a metal and non-metal.

3. This flows you over to the left side and the next question is does the

   cation have more than one oxidation number.

4. The answer is yes. Iron has two numbers 2 and 3.

5. We do not know from the formula which one is used, so we have to do

   a bit of math to determine the oxidation number.

6. At the bottom of the periodic table, back is a box labeled how to

   determine an oxidation number. You can see that it is the same

   formula.

7. Oxygen nearly always is a -2-oxidation number. Therefore, you can

   use this number multiplied by the number of oxygen present which is

   three (3) in number so the total negative charge is -6. All formulas

   unless otherwise indicated have a neutral or zero charge overall.
   8. Therefore, this means that the iron brings a +6 to the formula.

   9. As there are 2 iron atoms that means that each atom has a charge of

      +3.

   10.      Therefore you write the name of the cation with its oxidation

      number as a Roman numeral and follow it with the anion.

   11.      there are only two atoms present so it is a binary compound with

      an “ide” ending

                        Iron III oxide


                      Convert BaCO3 to a name

1. You ask is the compound ionic and yes it is.

2. Does the cation have more than one oxidation state?

3. You notice that it is in the second column on the left and all of these

   atoms have a +2 charge.

4. Now you notice that the name does not end in “ide” so you need to look

   on the back of the periodic table on the left side under the box labeled

   polyatomic ions.

5. You will find the most common ones, but this is not an exhaustive list.

6. Carbonate has the same formula and its charge is a -2.

7. so the cation is written first with the full name of the polyatomic anion

   written second

                        Barium carbonate
                    Convert Ni(NO3)2 to a name

1. This is the last of the bunch.

2. Look to see if it is an ionic compound.

3. It is ionic and you note that the name does not end in “ide”.

4. By now, you realize that you are dealing with a polyatomic ion, but you

   are not sure of the cation.

5. You look up Ni and you find that it is nickel and it has several oxidation

   states.

6. So just like the iron III oxide, you will need to do some math to

   determine which of the oxidation states you need to use.

7. You find the polyatomic ion on the back and you note that nitrate has a -

   1 charge.

8. The formula indicates that there are two nitrates present and that there

   is only one nickel present.

9. this makes it easier as the negative 2 must be balanced with w positive 2

   and because there is only one nickel atom present the charge on nickel is

   positive 2.

10. The name of the cation is written in full with the charge written as a

   Roman numeral and this is followed by the polyatomic anion with its

   name in full.
Nickel II nitrate