In a ground state atom of krypton (Kr), how many electrons have the angular momentum quantum number l = 2?

• A. 10
• B. 6
• C. 12
• D. 14

Answer: (A)

Verified step by step guidance

1. Recall that the angular momentum quantum number \(l\) corresponds to the shape of the atomic orbital: \(l=0\) is an s orbital, \(l=1\) is a p orbital, \(l=2\) is a d orbital, and \(l=3\) is an f orbital.
2. Identify the electron configuration of krypton (Kr), which has 36 electrons. The ground state electron configuration is \$1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6$.
3. Determine which orbitals have \(l=2\). Since \(l=2\) corresponds to d orbitals, only electrons in the 3d subshell contribute to this count.
4. Count the number of electrons in the 3d subshell from the configuration. The 3d subshell has \(10\) electrons, as indicated by \$3d^{10}$.
5. Conclude that the number of electrons with angular momentum quantum number \(l=2\) in a ground state krypton atom is the number of electrons in the 3d subshell, which is 10.