What are the formulas for the following compounds?

Question

1.) Ammonium Phosphate

2.) Barium Iodide

3.) Potassium Sulfate

4.) Lithium Sulfide

5.) Calcium Oxide

6.) Magnesium Carbonate


It would help if you explained to me how you did it....

Answer 1

The important thing is to look at the charges of the cations and anions.

Ex) Potassium Sulfate

Potassium = K. THis is the cation. It has a +1 charge because potassium likes to loose an electron to become like a noble gas
Sulfate= SO4 2- . Minus 2 charge. Should have this memorized as is a common polyatomic ion.

Thus, you need two +1 charges to balance the -2 of SO4
so the formula is K2SO4

ex 2) Barium Iodide

Ba (as a ion is +2)
I (as an ion is -1 as it wants to gain en electron to become a noble gas. All the elements in I's column form -1 ions. Stare at a periodic table and it will help)

BaI2

ex 3) Ammonium Phosphate.

These are both polyatomic ions that you should know or be able to look up.

Ammonium= NH4 +
Phosphate= PO4 3-

Remember, when writing you write in the form cation/anion so it will be

(NH4)3PO4

Answer 2

You need to look at the ionic charge of each ion or polyatomic ion and then use the criss cross method

The first two are as follows:

(NH4)3 PO4 because NH4 is +1 and PO4 is -3
K2 SO4 becasue K is +1 and SO4 is -2

You can do the rest.