Ionic Compounds 2
For example, sodium hydroxide is made of one sodium ion and one hydroxide ion:
Na+ and OH-
There is one sodium atom, one oxygen atom and one hydrogen atom for the sodium hydroxide molecule. It is not necessary
to show the chemical formula as Na+OH- . This is because the charge is balanced and the chemical formula is simply written as
Another example: What is the chemical formula for calcium hydroxide?
It can be seen from the Table on previous page that a calcium ion has positive two charge, whereas the hydroxide ion has a positive one charge. To get a net total of zero charge,
you need two hydroxide ions to cancel out the charge on one calcium ion. So, the chemical formula is
The bracket with a subscript two means there are two sets of OH- connected to calcium.