# Clarification of notation

by AxiomOfChoice
Tags: clarification, notation
 P: 529 I'm trying to decipher exactly what it means to say the following things: (1) The ground electronic state of NO$_2$ is $^{2}A_1$; (2) The ground electronic state of ClO$_2$ is $^{2}B_1$; (3) The ground electronic state of O$_2$ is $^{3}\Sigma^{-}_g$. I really don't have a clue what these symbols are supposed to mean. Can someone please help?