We're going to learn the difference between
inner core electrons and what are called valence
electrons.
What we're going to say here are valence electrons
are basically the electrons we found in the
outer most shell.
The outer most shells are usually the electron
orbitals with the biggest number.
Valence electrons are going to become more
important when we move over to bonding and
we have to draw chemical structures.
We have to realize there that all of the bonds
that we use to form chemical bonds are using
valence electrons.
We're going to say that main group metals,
whatever your main group metal number is,
that's also the number of valence electrons
that element has.
What do I mean by this?
For example, lithium, lithium is in group
1A, so lithium has one valence electron.
We're going to say for main group metals,
we're going to say valence electrons, so the
number of valence electrons equals group number.
These guys would have one valence, these guys
would have two valence, three valence, four
valence, five, six, seven and eight valence
electrons.
Except for helium.
Helium would have two valence electrons.
That's just for main metals.
Now, we know that the periodic table is not
made up of only main metals.
The periodic table is also made up of transition
metals.
When it comes to transition metals, they kind
of mess up everything.
For that part most professors seldom ask for
the number of valence electrons of a transition
metal.
But if they were to ask you the electron configuration
or valence electrons of a transition metal,
you just have to remember, for the most part
we can figure out the number of valence electrons
of these transition metals here.
The lanthanides and the actinides down here,
because they have f electrons, f orbital electrons,
we'd have to use quantum theory in order to
solve the number of valence electrons.
This is just chem one, so you don't have to
do quantum theory.
If they're going to ask you a number of valance
electrons for transition metals, it would
be these transition metals in here.
We'd simply say that their number of valence
electrons, so for transition metals, these
transition metals, we're going to say number
of valence electrons equals number of electrons
in the s and d orbitals.
By s I mean the highest numbered s.
The largest s orbital numbered and also the
d orbital.
Take those two, add them together and that
will give us our total number of valence electrons.
