An atom's atomic number is 7. Its valence is most likely:

• A. 3
• B. 7
• C. 5
• D. 1

Answer: (A)

Verified step by step guidance

1. Identify the element based on its atomic number. The atomic number 7 corresponds to the element nitrogen (N).
2. Recall that the valence of an atom is typically the number of electrons in its outermost shell (valence electrons) that can participate in bonding.
3. Determine the electron configuration of nitrogen: \$1s^2 2s^2 2p^3$. The outermost shell is the second shell, which contains 5 electrons (2 in 2s and 3 in 2p).
4. Understand that valence is often related to how many electrons an atom can lose, gain, or share to achieve a full outer shell (usually 8 electrons for main group elements).
5. Since nitrogen has 5 valence electrons, it tends to gain or share 3 electrons to complete its octet, so its valence is most likely 3.