Please help! I have an exam tomorrow, How do valence electrons affect how elements behave?

Hi, valence electrons are the number of electrons present in the outermost shells of atoms of elements, they affect how sharing or transfer of electrons takes place when the atoms go into any reaction.

they also determine the oxidation state of the atom.

for example, hydrogen has one electron in its outermost shell. therefore in any reactions it tends to loose that electron or gain one more to become stable.

the reason why elements go into reactions is to become stable (to have a complete duplet or octet structure).

As you know, each shells aside from the first has maximum of 8 electrons. so for a element like chlorine which have 7 electrons in the valence shell will gain one electrons in reactions to become stable(have a complete octet structure)

valence electrons also classifies elements( metal or non-metal)

if an element have 1, 2 or 3 valence electron(s), it is likely to be a metal

if an element have 4 or 5, it can be a non-metal or a metalliod (semiconductor)

if an element have 6 or 7, it is likely to be a non-metal

if an element have 8, it is a noble/inert gas

this also explains why noble gases do not react since they already have a duplet structure, they do not need to go into reaction.

good lucks on your exams.