What type of bond forms when a sodium atom with one valence electron reacts with a chlorine atom with seven valence electrons?

• A. Covalent bonding
• B. Repulsion
• C. Attraction
• D. Ionic bonding

Answer: (D)

The key idea is that when a metal with just one valence electron meets a nonmetal that needs electrons to complete its outer shell, the metal tends to lose electrons and the nonmetal tends to gain them. Sodium has one valence electron and chlorine needs one to reach a full octet. Sodium donates its single electron to chlorine, forming Na+ and Cl−. The resulting ions are held together by a strong electrostatic attraction between their opposite charges, which is what we call an ionic bond. This is typical of reactions between metals and nonmetals where electron transfer creates stable charged ions. Covalent bonding would involve sharing electrons rather than transferring them, and repulsion isn’t a bonding type, while attraction is too general to specify the kind of bond formed.