00:03
Hi there.
00:04
As we look at the periodic table, we realize that several of the representative elements, or the main group elements, form ions with a single charge.
00:14
For example, everything in group one, the alkali metals.
00:19
They all have one valence electron, so when they form an ion, they will lose that one valence electron and always form an ion with a one plus charge.
00:28
The alkaline earth metals are similar, and they will form, but they will form ions with a one -plus electron.
00:33
2 plus charge because they have two valence electrons to lose.
00:39
In group 3a, aluminum and gallium anyway will form ions with a 3 plus charge.
00:48
While when we get to the non -metals, the non -metals gain electrons.
00:52
So the group where we find nitrogen, group 5a, they have 5 valence electrons.
00:58
So to get to an octet of 8, they want to gain 3.
01:02
So they will form ions with a 3 negative charge.
01:06
Oxygen's group, they will form ions with a two negative charge, and the halogens will form ions with a one negative charge.
01:16
So let's look at the elements that we have here.
01:19
In this question, we have oxygen.
01:22
So we know oxygen only forms one ion with a two negative charge.
01:26
We also have calcium.
01:28
It always forms an ion with a two positive charge...