Determine the electron configurations for CN+, CN, and CN-. (b) Which species, if any, has unpaired electrons?

Verified step by step guidance

1. Identify the total number of electrons in each species. CN+ has one less electron than the neutral CN molecule, while CN- has one more electron. The neutral CN molecule has a total of 13 electrons (7 from nitrogen and 6 from carbon). Therefore, CN+ has 12 electrons and CN- has 14 electrons.
2. Write the electron configurations for carbon (C) and nitrogen (N) separately. Carbon has an atomic number of 6, so its electron configuration is 1s^2 2s^2 2p^2. Nitrogen has an atomic number of 7, so its electron configuration is 1s^2 2s^2 2p^3.
3. Combine the electron configurations of carbon and nitrogen to form the molecular orbitals for CN. Start filling the molecular orbitals in order of increasing energy: σ(1s), σ*(1s), σ(2s), σ*(2s), π(2p), σ(2p), π*(2p), σ*(2p).
4. Distribute the electrons among the molecular orbitals for each species. For CN+, distribute 12 electrons; for CN, distribute 13 electrons; and for CN-, distribute 14 electrons. Remember that each orbital can hold a maximum of two electrons with opposite spins.
5. Determine the presence of unpaired electrons by examining the electron configurations of each species. If an orbital contains only one electron, it is unpaired. Check the highest energy orbitals in each species to see if any have unpaired electrons.

Key Concepts

Electron Configuration

Electron configuration describes the distribution of electrons in an atom or ion across various atomic orbitals. It follows the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level to higher ones. The notation typically includes the principal quantum number, the type of orbital, and the number of electrons in that orbital, such as 1s² 2s² 2p⁶.

Ionic Charge and Electron Count

The ionic charge of a species affects its electron count. For neutral molecules, the number of electrons equals the number of protons. However, for cations (like CN+), electrons are removed, while for anions (like CN-), electrons are added. Understanding how to adjust the electron count based on the charge is crucial for determining the correct electron configuration.

Unpaired Electrons

Unpaired electrons are those that occupy an orbital alone rather than in pairs. The presence of unpaired electrons is significant as it influences the magnetic properties of a species, making it paramagnetic. To identify unpaired electrons, one must analyze the electron configuration and look for orbitals that contain a single electron.