Configurations such as 2p_x(↑↓) and 2p_x(↑) 2p_y(↓) can still occur in the C atom but not in its ground state. The ground state, with the two unpaired 2p electrons, is called a triplet state. States with energies higher than the ground state are called excited states. In this case, because the electrons have the same spin and there are no unpaired electrons, the first excited states of the C atom are called singlet states.