Final answer:
Valence electrons are the ones available for bonding in an atom. These electrons participate in different types of bonds, including ionic bonds, where electrons are transferred, and covalent bonds, where electrons are shared between atoms.
Step-by-step explanation:
The type of electron available to form bonds is the valence electron. Valence electrons are the outermost electrons of an atom and are responsible for the chemical properties of the element, including its ability to form bonds. When an atom donates an electron to another atom, it becomes a cation, which has a positive charge.
Molecules form by two main types of bonds: the ionic and covalent. In ionic bonding, an atom donates an electron to another, creating ions with opposite charges that attract each other. In covalent bonding, atoms share electrons to achieve a full valence shell, leading to the formation of molecules.