Answer: Valence Electrons are basically how many electrons are in the outer shell of electrons.
Step-by-step explanation:
Take Hydrogen, it has 1 valence electron because in the outermost shell it has 1 electron. Take Argon, which is a noble gas. All of the noble gasses are incredibly stable and do not like to react. This is because they all have a full set of valence electrons. While Sodium is an Alkali metal, and each element only has one valence electron so they react violently.