How many valence electrons does a copper (Cu) atom have?

• A. 1
• B. 2
• C. 10
• D. 8

Answer: (A)

Verified step by step guidance

1. Identify the electron configuration of a neutral copper (Cu) atom. Copper has an atomic number of 29, so it has 29 electrons.
2. Write the electron configuration for copper: \$1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10}$.
3. Recall that valence electrons are the electrons in the outermost shell (highest principal quantum number, n). For copper, the outermost shell is the 4th shell, which contains the \$4s^1$ electron.
4. Note that the \$3d^{10}\( electrons are in the third shell and are considered part of the transition metal's d-subshell, which can sometimes contribute to valence behavior, but typically only the \)4s$ electron is counted as valence for copper.
5. Conclude that copper has 1 valence electron, corresponding to the single electron in the \$4s$ orbital.