How many valence electrons does a sodium (Na) atom have?

• A. 8
• B. 0
• C. 1
• D. 2

Answer: (C)

Verified step by step guidance

1. Identify the atomic number of sodium (Na), which is 11. This means a neutral sodium atom has 11 electrons.
2. Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom.
3. Determine the electron configuration of sodium: \$1s^2 2s^2 2p^6 3s^1$.
4. Note that the outermost shell for sodium is the third shell (3s), which contains 1 electron.
5. Conclude that sodium has 1 valence electron because only the electrons in the outermost shell count as valence electrons.