An ionic bond forms between an elemental metal and non-metal, characterized by the transfer of electrons from the metal to the non-metal in an attempt to mimic the stable octet.
A is the correct answer, as Potassium (a group 1 alkali metal) will donate an electron to Chlorine (a group 17 halogen). Potassium becomes more stable by removing the outermost shell, leaving behind a stable octet, and Chlorine completes its shell with the addition of the new electron. This trade of electrons forms their “ionic” forms, hence the reason for calling it an ionic bond. The other three form covalent bonds.
