How do you tell how many VALANCED electros an element has?

Question

for example beryllium?

Answer 1

u look at the hghest possible energy level their is and count all of its electrons and those are u'r valence electrons

the defination of valence electron is the electrons in the last possible energy level.

for example

halogens all have 7 valence electrons , that is becuse they all are one electron away from reaching octate.

Answer 2

Be is in Group IIA (or Group 2), so it has 2 valence e-.

For the "A" family elements, the number of valence e- is the same as the group number.

IA = 1; IIA = 2; IIIA = 3; IVA = 4; VA = 5; VIA = 6; VIIA = 7; Nobel Gases = 8 (except He = 2)

For the 2nd period elements:

Li = 1

Be = 2

B = 3

C = 4

N = 5

O = 6

F = 7

Ne = 8

Answer 3

You can count over from the left hand side of the row in the periodic table that the element is in.  Beryllium, for example, is two elements over in its row in the table.  This means it would have two valence electrons in a pure, elemental state.  Oxygen is 1,2,3,4,5,6 elements away from the left side (ignore the empty spaces above the transition metals), so it has six valence electrons in its elemental form.