Which element is most likely to form exactly three covalent bonds with hydrogen atoms?

• A. Phosphorus
• B. Nitrogen
• C. Oxygen
• D. Carbon

Answer: (B)

Verified step by step guidance

1. Understand that the number of covalent bonds an element typically forms depends on its valence electrons and the octet rule, which states atoms tend to have eight electrons in their valence shell through bonding.
2. Recall the valence electron count for each element: Nitrogen has 5 valence electrons, Phosphorus has 5, Oxygen has 6, and Carbon has 4.
3. Determine how many electrons each element needs to complete its octet: Nitrogen needs 3 more electrons, Phosphorus also needs 3, Oxygen needs 2, and Carbon needs 4.
4. Since hydrogen can form only one covalent bond (it needs 1 electron to complete its duet), the element that needs exactly 3 electrons to complete its octet will form 3 covalent bonds with hydrogen atoms.
5. Conclude that both Nitrogen and Phosphorus can form 3 bonds, but Nitrogen is more commonly known to form exactly three covalent bonds with hydrogen atoms (as in ammonia, NH₃), making it the most likely answer.