What type of bond involves the sharing of valence electrons between all atoms in a metal?

The correct answer is the type of bond known as a metallic bond. This bond is characterized by the sharing of valence electrons among a lattice of metal atoms. In metallic bonding, electrons are not localized to individual atoms but instead are delocalized, creating a "sea of electrons" that move freely throughout the structure. This mobility of electrons allows metals to conduct electricity and heat effectively and contributes to their malleability and ductility.

In a metallic bond, the positive metal ions are surrounded by these delocalized electrons, which act as a cushion, enabling the metal to maintain its structure under stress. This is why metals can bend without breaking and can conduct electricity well, as the electrons can move to carry charge.

The other types of bonds listed do not share this characteristic. Covalent bonds involve the sharing of electrons specifically between two nonmetal atoms, ionic bonds involve the transfer of electrons from one atom to another resulting in charged ions, and polar bonds are a type of covalent bond where the shared electrons are not shared equally, resulting in partial charges on each of the atoms involved.