Which of the following electron configurations for a neutral carbon atom represents an excited state?

• A. 1s^2 2s^2 2p^1 3p^1
• B. 1s^2 2s^2 2p^2
• C. 1s^2 2s^1 2p^3
• D. 1s^2 2s^2 2p^1 3s^1

Answer: (C)

Verified step by step guidance

1. Step 1: Recall that the ground state electron configuration of a neutral carbon atom (atomic number 6) is the arrangement of electrons in the lowest possible energy levels. For carbon, this is \$1s^2 2s^2 2p^2$.
2. Step 2: Understand that an excited state occurs when one or more electrons are promoted to higher energy orbitals than in the ground state, resulting in a configuration with electrons in orbitals that are normally empty or partially filled at higher energy levels.
3. Step 3: Examine each given configuration and compare it to the ground state configuration. Identify if any electrons have been moved from a lower energy orbital to a higher energy orbital.
4. Step 4: For example, the configuration \$1s^2 2s^1 2p^3\( shows that one electron from the \)2s\( orbital has been promoted to the \)2p\( orbital, increasing the number of electrons in \)2p\( from 2 to 3 and decreasing \)2s$ from 2 to 1. This indicates an excited state.
5. Step 5: Confirm that other configurations either match the ground state or involve electrons in orbitals that are not typical for carbon's ground state, such as \$3p\( or \)3s$, which also indicate excited states. The key is to identify which configuration represents a valid excited state based on electron promotion.