How many valence electrons does a boron (B) atom have?

• A. 3
• B. 4
• C. 2
• D. 5

Answer: (A)

Verified step by step guidance

1. Identify the atomic number of boron (B), which is 5. This means a neutral boron atom has 5 electrons.
2. Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom.
3. Determine the electron configuration of boron: 1s\^2 2s\^2 2p\^1.
4. Recognize that the first shell (1s) is the inner shell and the second shell (2s and 2p) is the outermost shell for boron.
5. Count the electrons in the outermost shell: 2 electrons in 2s and 1 electron in 2p, totaling 3 valence electrons.