Valence electrons drive ionic compound formation Steps:

• Ionic compounds form via electron transfer from metal to nonmetal.
• Metals (low electronegativity) have 1–3 valence electrons and donate them easily.
• Nonmetals (high electronegativity) have 5–7 valence electrons and accept electrons to fill octets.
• Thus, nonmetal atoms always have more valence electrons than metal atoms.

Why B is correct:

• Nonmetals require fewer electrons to complete their octet, so their atoms start with more valence electrons than metal atoms, as per octet rule.

Why the others are wrong:

• A: Ions of X could be positive if X is the metal (cation).
• C: Ionic compounds often involve elements from different periods, like Na (period 3) and F (period 2).
• D: Metals and nonmetals belong to different groups (e.g., group 1 vs. group 17).

Final answer: B