How many valence electrons does a calcium (Ca) atom have?

• A. 6
• B. 2
• C. 1
• D. 8

Answer: (B)

Verified step by step guidance

1. Identify the element in question, which is calcium (Ca).
2. Recall that valence electrons are the electrons in the outermost shell of an atom.
3. Determine the electron configuration of calcium. Calcium has an atomic number of 20, so it has 20 electrons.
4. Write the electron configuration for calcium: \$1s^2 2s^2 2p^6 3s^2 3p^6 4s^2$.
5. Identify the electrons in the outermost shell, which is the 4th shell (4s orbital), and count them. These are the valence electrons.