Hi, this is Dr. B. Let's do the Lewis structure
for NH4+, the ammonium ion.
So Nitrogen, on the periodic table, is in
group 5, so it has 5 valence electrons.
Hydrogen, group 1; we've got 4 of these, though;
four Hydrogens, so let's multiply that times
4.
And if you see a plus sign, that means you've
lost a valence electron.
So we've lost one, that's minus one.
And 5 plus 4 is 9, minus 1, that's going to
be 8.
So we have eight total valence electrons.
Let's put Nitrogen here.
We know that Hydrogen always goes on the outside,
so there they go; and we've got four of them.
So we'll put those four there.
Now what we want to do is put some chemical
bonds here.
We have eight valence electrons so we'll put
2, 4, 6, 8.
And if we check our octets, Hydrogen only
needs 2.
So the Hydrogens, they're OK, they all have
2 valence electrons.
Nitrogen needs eight valence electrons for
a full outer shell, or an octet, and Nitrogen
has 8.
So we're good.
That is the structure for NH4+, the ammonium
ion.
The only thing we have to do though is, we
like to put these brackets around it like
this and put a plus sign up there.
So if you drew that real nice as a structural
formula, that would look like this right here
where the brackets are just making sure you
remember that is going to be a plus sign because
we lost this electron up here.
We have to take account for that.
That's the Lewis structure for NH4+.
This is Dr. B., and thanks for watching.
