Chlorine forms which ion?

Chlorine forms which ion?

• A. Cl -
• B. Cl +
• C. Cl 2-
• D. Cl 3-

Answer: (A)

This question is about how nonmetals like chlorine typically form ions. Halogens gain electrons to reach a full outer shell, giving a negative ion. Chlorine has seven electrons in its outer shell, so it readily gains one more to achieve a stable octet, becoming the chloride ion, Cl-. This is why in salts such as sodium chloride, chlorine ends up with a −1 charge. The other possibilities would require chlorine to lose electrons or gain many more electrons than one, which is not favored energetically for a halogen. Losing electrons would create a positively charged ion, which is uncommon for chlorine in ordinary compounds, and gaining two or three electrons would produce ions that aren’t stable or typical for chlorine.

This question is about how nonmetals like chlorine typically form ions. Halogens gain electrons to reach a full outer shell, giving a negative ion. Chlorine has seven electrons in its outer shell, so it readily gains one more to achieve a stable octet, becoming the chloride ion, Cl-. This is why in salts such as sodium chloride, chlorine ends up with a −1 charge.

The other possibilities would require chlorine to lose electrons or gain many more electrons than one, which is not favored energetically for a halogen. Losing electrons would create a positively charged ion, which is uncommon for chlorine in ordinary compounds, and gaining two or three electrons would produce ions that aren’t stable or typical for chlorine.