Advanced Placement (AP) Chemistry Practice Exam 2025 - Free AP Chemistry Practice Questions and Study Guide

The correct electron configuration for nitrogen is indeed 1s² 2s² 2p³. To understand why this is accurate, it's essential to consider the atomic structure of nitrogen.

Nitrogen has an atomic number of 7, indicating that it has seven electrons. The arrangement of these electrons in atomic orbitals follows the principles of the Aufbau principle, Pauli exclusion principle, and Hund's rule.

The Aufbau principle states that electrons fill orbitals starting from the lowest energy level to the highest. Thus, the first two electrons will fill the 1s orbital (1s²). After that, the next two electrons will occupy the 2s orbital (2s²). This accounts for the first four electrons.

Now, for the next three electrons, they will be added to the 2p orbital. Since there are three electrons remaining after filling the 1s and 2s orbitals, this results in a configuration of 2p³. Each electron in the 2p subshell occupies its own orbital (following Hund's Rule to minimize electron repulsion), which leads to three electrons in the 2p subshell.

Therefore, the complete electron configuration for nitrogen becomes 1s² 2s²