2p2

2p2 denotes an electronic configuration in which two electrons occupy the 2p subshell of an atom. In neutral carbon, the ground-state configuration is 1s2 2s2 2p2, reflecting two electrons in the second shell’s p subshell that participate in bonding and chemical behavior. The 2p2 arrangement is a common reference point for describing carbon’s valence structure and related spectroscopy.

In terms of quantum mechanics, the two electrons in a p2 configuration can combine to form distinct term symbols under LS coupling. The allowed terms are 3P, 1D, and 1S, with 3P typically being the lowest-energy term for p2. For a 3P term, the total spin quantum number S equals 1 and the total orbital angular momentum L equals 1, giving possible total angular momentum values J = 0, 1, 2. For neutral carbon, the ground state is 3P0, the lowest J sublevel of the triplet P term.

Occasionally, 2p2 appears in ions or isoelectronic species. For example, nitrogen with a +1 charge (N+) is isoelectronic with carbon and also has a 2p2 configuration. The 2p2 arrangement influences the spectral lines observed in astrophysical and laboratory spectroscopy and is relevant to the study of early transition-period elements.

Significance extends to chemistry and materials science. The two 2p electrons contribute to carbon’s valence and its ability to form covalent bonds, underpinning a wide range of organic compounds. The state of these electrons also affects magnetic properties, ionization energies, and the detailed structure of carbon’s electronic spectrum.