Which factor primarily determines the number of covalent bonds that an atom can form?

• A. The atomic mass of the element
• B. The total number of protons in the nucleus
• C. The atom's electronegativity value
• D. The number of unpaired electrons in the atom's valence shell

Answer: (D)

Verified step by step guidance

1. Understand that covalent bonds form when atoms share electrons, specifically from their valence (outermost) electron shell.
2. Recall that the number of covalent bonds an atom can form depends on how many electrons it can share to complete its valence shell, often aiming for an octet (8 electrons) in many cases.
3. Identify that the key factor is the number of unpaired electrons in the valence shell because each unpaired electron can form one covalent bond by pairing with an electron from another atom.
4. Recognize that atomic mass and the total number of protons do not directly influence bonding capacity; they relate more to the identity and stability of the atom rather than bonding behavior.
5. Note that electronegativity affects bond polarity and bond strength but does not determine how many bonds an atom can form; the bonding capacity is primarily set by the number of unpaired valence electrons.