The number of valence electrons is just how many electrons an atom has in its outer shell. It's easy to figure out if you've got a Periodic Table.
(See the link below this answer for a good periodic table).
All the elements in each column have the same number of electrons in their outer shells. All the elements in the first column all have a single valence electron (H, Li, Na, K, etc.).
The second column elements all have 2 valence electrons (Be, Mg, Ca, Sr, etc.).
Skipping over the gap, go to the Group 3 elements, which all have 3 valence electrons (B, Al, Ga, etc.).
The elements in the next column (C, Si, Ge, etc.) all have 4 valence electrons.
The elements in the next column (N, P, As, etc.) all have, yes, you guessed it, 5 valence electrons.
O, S, Se, and the others in this column have 6 valence electrons.
The halogens in the next-to-last column (F, Cl, Br, etc.) have 7 valence electrons.
The noble gases in the right-most column (Ne, Ar, Kr, etc.) all have 8 electrons in their out except for He, which only has 2 electrons.
In column 1 all of those elements have 1 valence electron.
In column 2 there are 2 valence electrons. He(Helium) is included here.
Skip columns 3 to 12 because their valence electrons vary.
Column 13 has 3 valence electrons.
Column 14 has 4 valence electrons.
Column 15 has 5 valence electrons.
Column 16 has 6 valence electrons.
Column 17 has 7 valence electrons.
Column 18,except for He(Helium), has 8 valence electrons.
There are 2 valence electrons in an atom of magnesium. There are 5 valence electrons that are in an atom of phosphorus. There are 4 valence electrons that are in a silicon atom.
Oxygen as 6 valence electrons.See the Related Questions for how to count the valence electrons of any atom.
The electrons farthest away from the nucleus are the valence electrons of an atom.
The valence electrons are the electrons in the outer shell of an atom.
Valence electrons are those in the outermost shell of the atom.
The valence electrons occur in what part of the atom?
there are five valence electrons in an atom of phosphorus
A nitrogen atom has 5 valence electrons.
valence electrons are the electrons located in the outer shell of an atom which are available for reaction
nitrogen has 5 valence electrons. carbon has 4 valence electrons.
each period (row) on a periodic table represents the outermost ring of electrons (valence electrons). Well if you count across a period you will get the number of valence electron. For example, if you count across a period for Oxygen (O atomic number:8) you will count 6 which is the amount of valence electrons in oxygen
The electrons in the outermost shell of an atom is known as the valence electrons. These valence electrons determine the reactivity of the atom.