Chapter 2 - Small Molecules and the Chemistry of Life - 2.1 - Atomic Structure Explains the Properties of Matter - 2.1 Recap - Learning Outcomes - Page 28: 2

Valence electrons are electrons on the outermost orbital of an atom that allows the atom to participate in bonding with other atoms. The valence number increases as you go down each group of a period (a row on the periodic table). Carbon has 4 valence electrons, oxygen has 6 and helium has 2. Helium's 2 electrons form a full valence shell, making the atom extremely inert.

Valence electrons are electrons on the outermost orbital of an atom that allows the atom to participate in bonding with other atoms. The valence number increases as you go down each group of a period (a row on the periodic table). Carbon has 4 valence electrons, oxygen has 6 and helium has 2. Helium's 2 electrons form a full valence shell, making the atom extremely inert.