Valence electrons are the electrons in the outermost shell (valence shell) of an atom. When atoms bond with each other, they interact through the sharing, gaining, or losing of valence electrons. The way valence electrons are organized determines the type of bond that forms between atoms. There are three primary types of chemical bonds:
Covalent Bond: In a covalent bond, atoms share one or more pairs of electrons. This type of bond occurs when two nonmetal atoms come together. The shared electrons are attracted to the nuclei of both atoms, creating a stable arrangement. Covalent bonds can be either single, double, or triple, depending on the number of electron pairs shared between the atoms.
Ionic Bond: An ionic bond forms when there is a transfer of valence electrons between atoms. This occurs between a metal and a nonmetal atom. The metal atom loses one or more valence electrons, forming a positively charged ion (cation), while the nonmetal atom gains the electrons, forming a negatively charged ion (anion). The resulting attraction between oppositely charged ions leads to the formation of an ionic bond.
Metallic Bond: Metallic bonding occurs within metals, where valence electrons are delocalized and move freely throughout the entire crystal lattice. The valence electrons are shared among all the atoms in the metallic structure, creating a "sea" of electrons that hold the positively charged metal ions together.
These different types of bonds are a result of the arrangements and interactions of valence electrons, and they determine the chemical properties and behaviors of substances.