| if u mean the letters given to the quantum numbers, they are K L M N. well the K can keep 2 electrons, L can keep 8, M 18, and N also can keep 18 electrons. the energy increases in the following order, K L M N. but the energy difference becomes less as we go K L M N . the K deals with the Liman , L with the Bharmer, M with Paschen and N with Brackket group. |