How do you find the number of Valence electron?

[mcmcdaniel]

How do you determine the number of Valence electron especially for the transition metals. Is there an equation i have to do?

[folubunmi]

Electron configuration.

Then the last shell's sum of the orbitals electrons you get determines the number of valence electrons.

[Mimi]

Valence Electrons are the Electrons available for bonding.

Having said that, the periodic table is itself the best way to determine the number of Valence Electrons in an particular element. Electrons are arranged in Orbits (I dont know how much knowledge you have in Chemistry - They usually tell you different things regarding the structure of an Atom to understand the basics, then they tell you the truth).

An orbit is simply a volume of space in which a particular electron exists. There are different orbits based on different energy levels - further the electron from the nucleus lower is the energy level of its Orbit.

Now, there are various energy levels and some overlap each other.
For Group 1 Elements, there is 1 Valence Electron
For Group 2 Elements, there are 2 Valence Electrons

For Group 13 Elements, there are 3 Valence Electrons
And so on until Group 18 which have 8 Valence Electrons.

Now I deliberately left out Group 3 - 12 because they have the overlap in energy level.
Now the overlap is between the orbits: s & d

Normally it goes s, p, d with the energy level infront - so 1s, 1p, 1d and then 2s, 2p, 2d. Transition metals will have something like this at a certain energy level 4s, 3d. Wierd huh?

The 4s is the highest level hence the only one that should count. Valence eletrons are the one that are furtherst / outmost orbit and hence highest level. in the 4s3d case, its only the electrons in the 4s that count.

Hope that helps and I didn't confuse you. If it did I'd do my best to explain it better.

[Awilson837]

count the electrons in the s and p sublevels. or just count the "outer" boxes on your periodic table. if you look at it, there's a big block of elements in the middle. ignore those! if you count the outer boxes only, you'll notice they add up to eight. so a noble gas, such as neon which is in the eighth group, will have all 8 valence electrons, which is the most any element can have. chlorine, which is in group 7, has 7 valence electrons.