What are the likely ground-state electron configurations of the following anions? (a) Se^2- (b) N^3-

Verified step by step guidance

1. Identify the atomic number of the neutral atom. Selenium (Se) has an atomic number of 34, and nitrogen (N) has an atomic number of 7.
2. Determine the electron configuration of the neutral atom. For Se, the electron configuration is [Ar] 3d^{10} 4s^{2} 4p^{4}. For N, it is 1s^{2} 2s^{2} 2p^{3}.
3. Add electrons to account for the charge of the anion. For Se^{2-}, add 2 electrons to the neutral Se configuration, resulting in [Ar] 3d^{10} 4s^{2} 4p^{6}. For N^{3-}, add 3 electrons to the neutral N configuration, resulting in 1s^{2} 2s^{2} 2p^{6}.
4. Recognize that adding electrons to the p orbitals fills them to their maximum capacity, achieving a noble gas configuration. Se^{2-} achieves the configuration of Kr, and N^{3-} achieves the configuration of Ne.
5. Verify that the resulting electron configurations correspond to stable, filled-shell configurations, which are characteristic of noble gases.

Key Concepts

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It follows the Aufbau principle, which states that electrons fill the lowest energy orbitals first, and is represented using a notation that indicates the energy levels and sublevels occupied by electrons. Understanding electron configuration is essential for predicting the chemical behavior and properties of elements and ions.

Anions and Charge

Anions are negatively charged ions formed when an atom gains one or more electrons. The charge of an anion indicates the number of additional electrons compared to the neutral atom. For example, Se^2- has gained two electrons, while N^3- has gained three, which affects their electron configurations and overall stability.

Ground-State Configuration

The ground-state configuration refers to the lowest energy arrangement of electrons in an atom or ion. For anions, this configuration is determined by adding the extra electrons to the existing configuration of the neutral atom. Understanding how to derive the ground-state configuration is crucial for accurately determining the electron arrangements of anions like Se^2- and N^3-.