Tip:
Highlight text to annotate it
X
Going further into ionic bonds and chemical bonds,
you may be asked a problem.
Such as, how many electrons are used
to draw an electron dot structure. Well,
if you recall from a previous video, I drew out a little piece of the periodic table
and I told you remember the pattern 1, 2, 3, 4, 3, 2, 1.
Remember that the first 1, 2, 3, 4 that's positive, the second 3, 2, 1 that's negative.
This goes into your lewis dot structures.
So a positive one means that everything in that column has one valence electron to give up.
A positive 2 means that everything in that column, beryllium, magnesium has two to give up.
On the flip side,
fluorine has a negative one, meaning it wants to take on one.
Oxygen has a negative two, meaning it wants to take on two more electrons for its valent shell.
So let's look at a sample problem here,
that you may see. So this problem says, how many electrons are used to draw
the electron dot structure for propane?
So propane is
"C3H8"
and this question is
actually asking you, how
many valence electrons? If you go back to your periodic table,
you can recall that carbon
each has four and then
every single hydrogen has one.
So you'll see when you draw it out
that
every single carbon
bonds to a carbon and a hydrogen
and that's where you get your "C3H8"
So how many total do we need here?
Just count them up.
2, 4, 6, 8, 10, 12, 14, 16, 18, 20,
20 electrons to make propane