Here's why:

* Valence Electrons: These are the electrons found in the outermost shell of an atom. They are the ones most loosely held and thus most likely to interact with other atoms.

* Bonding: Chemical bonds are formed when atoms share or transfer valence electrons.

* Covalent Bonds: Atoms share valence electrons.

* Ionic Bonds: One atom transfers one or more valence electrons to another atom.

Key points to remember:

* The number of valence electrons an atom has determines its bonding behavior.

* Atoms tend to gain, lose, or share valence electrons to achieve a stable electron configuration, typically with a full outer shell of electrons (like the noble gases).

Let me know if you'd like a more detailed explanation of any of these concepts!