An atom with seven valence electrons is most likely a(n)?

• A. Conductor
• B. Insulator
• C. Semiconductor
• D. Metalloid

Answer: (B)

Valence electrons determine how easily electrons can move to carry an electric current. An atom with seven valence electrons is in the nonmetal group known as the halogens. These elements are highly nonmetallic and, in solid form, do not have freely moving electrons to conduct electricity, so they behave as insulators. They also tend to gain one electron to complete a full octet rather than lose electrons to become conductive. Semiconductors and metalloids usually have different, intermediate conduction properties tied to having four or five valence electrons in many common examples, so they don’t fit the seven-valence-electron case.