How to determine the number of valence electrons in an element?
Valence electrons are electrons located in the outermost shell of an atom.
Valence electrons are the most important electrons because they are the electrons involved in chemical reactions.
The easiest way to figure out how many valence electrons there are in an element is to use the periodic table.
The periodic table shows the valence group 1 to 8.
For example, the elements in group 1 (going down the column) have 1 valence electron:
hydrogen (H), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), Francium (Fr)
The noble gases that have 8 valence electrons are:
helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn)
Valence electrons are very important for atoms bonding.
For transition metals, figuring out the valence electrons is more complicated. The valence electrons occur in more than one shell and are not necessary in the outermost shell.