Question

30 which of the following orbital notations for phosphorus is correct? * (0.5 points) a. 1s ↑↓ 2s ↑↓ 2p ↑↓↑↓↑↓ 3s ↑↓ 3p ↑↓↑↑□ b. 1s ↑↓ 2s ↑↓ 2p ↑↓↑↓↑↓ 3s ↑↑ 3p ↑↑↑↑ c. 1s ↑↓ 2s ↑↓ 2p ↑↓↑↓↑↓ 3s ↑↓ 3p ↑↑↑↑ d. 1s ↑↓ 2s ↑↓ 2p ↑↓↑↓↑↓ 3s ↑↓ 3p ↑↑□ b c d a

Explanation:

Step1: Recall phosphorus electron - configuration

Phosphorus has an atomic number of 15. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$.

Step2: Apply Hund's rule

According to Hund's rule, electrons in degenerate orbitals (such as the three 3p orbitals) first fill each orbital singly with parallel spins before pairing up.

Step3: Analyze each option

• Option a: In the 3p orbitals, electrons are paired up before filling all orbitals singly, which violates Hund's rule.
• Option b: The 3s orbital has only one electron instead of two, which is incorrect for phosphorus.
• Option c: This option correctly shows the electron - configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$ with electrons in the 3p orbitals filling singly with parallel spins.
• Option d: The 3s orbital has only one electron instead of two, which is incorrect for phosphorus.

Answer:

C