00:01
All right, so i've drawn a periodic table here, and we have the first column, the second column, then we're going to skip the middle, and when it comes back up again, we have six more columns.
00:16
And what i did was i wrote the numbers one through eight in those to denote the number of valence electrons that elements in that column have.
00:28
So everything in this column has one, everything in this column has two, and so forth.
00:34
And the reason that we care about the number of valence electrons is this thing called the octet rule, that elements want to have eight electrons in their valence shell.
00:46
And they can get that by either adding or subtracting electrons from their outermost shell.
00:53
Valence electrons are the outermost shell.
00:56
If the number is less than four, elements like to lose electrons.
01:02
If it's greater than five, they like to gain electrons.
01:07
And if it's four, we're not exactly sure.
01:11
So if this first column has elements with one electron and it wants to get rid of that electron, it gets rid of a negative thing.
01:20
So it becomes more positive, plus one.
01:24
If this one will lose two electrons, it becomes more positive by two because it gave away two negative things.
01:32
In column three, we would give away three negative things, so we would overall be positive three.
01:40
When we get to five, to get to eight, what it's going to want to do is gain three electrons, gain three negative things.
01:48
It'll be negative three.
01:50
For six electrons, it'll want to gain two, two negative things...