How to figure out how many valence electrons in an elements outer ...

[plus1]

In science I presume that when things are written like this:

Li
)  )  )
1 2 3
)  )  )

(Numbers not correct) I guess this is stating how many valence electrons are in each shelf. How do you figure out how many valence electrons are in each shelf?

[aero]

You need to look at the periodic table.
The periodic table is split into columns and rows, with the columns called groups and the rows periods.

The first group has one valence electron.
The last group (group 18) has a full valence shell.

So every thing in the first column has only one valence electron in its neutrally charged state.

Sometimes it is easiest if we just go through them
Hydrogen has one valence electron, because it is group 1.
Helium, the next element over has two valence electrons, and because it is in period 1, it completes its shell.

Lithium has the first shell completed, then one valence electron.  Beryllium has two valence electrons, boron three, carbon four, nitrogen five, oxygen six, fluorine seven, and since neon is in the las group it has the full eight valence electrons.
This continues with period 3
It gets shaken up with period 4 because this is where the transitional metals are introduced, so group four and five have 18 valence electrons.

Groups six and seven introduce the lanthinide and actinide series so I think there are 32 valence electrons total in group 18 of period 6 & 7.

[sammy]

The periodic Table of Elements gives you the 'Atomic Number' of each Element.
This is the No. of Protons and therefore the No. of Electrons in the Atom.
Below, is the list of the Shell Letters for Atoms.
Starting with Hydrogen, we have 1 proton = 1 Electron meaning that Hydrogen has only 1 Shell ..the 'K' shell with 1 electron in it...the Valence electron.
If, in the Table of Elements, you look for say, 'Bromine' (Br).
You will find that its Atomic No. = 35; = 35 protons and 35 electrons. Using the following list, you can find the number of shells and MAXIMUM No. of electrons in each shell for Bromine.

K. Shell = 2 Electrons.
L. Shell = 8
M. Shell =18
N. Shell = 32
O. Shell = 50  *
P. Shell = 72  *    
Q. Shell = 98  *          
 * =  Theoretical  Capacity
From this list, Bromine with 35 electrons will be:
K = 2, L = 8, M = 18 and N = 7; (1 less than a full shell).
Valence Electrons are only found in the OUTER shell.
In the Periodic Table, you will find that 'Br' has a valence of 1 as do all the Halogens. (Shell 'N' can take 1 more electron to become full and take on the same 'N' shell configuration as 'Krypton' (Kr), the Inert, Noble gas...('Kr' is Non-reactive, having no valence electrons).