Question

which of the following elements would need to appear as a diatomic molecule when not bonded to another element?
helium
sulfur
iodine
phosphorus

Explanation:

• Helium is a noble gas with a full valence shell, so it exists as single atoms (\(He\)).
• Sulfur typically forms \(S_8\) molecules in its elemental form (not diatomic).
• Iodine is one of the diatomic elements (\(I_2\)). The diatomic elements can be remembered by the mnemonic "BrINClHOF" (Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, Fluorine).
• Phosphorus usually forms \(P_4\) molecules in its elemental form (not diatomic).

Answer:

C. Iodine