Give the electron configuration for sodium (na, element number 11). in what atomic orbital does the electron with the most energy reside?
the electron configuration you just wrote for the sodium atom describes the element in its lowest energy or ground state. each of the atomic orbitals for an element is separated from the next by a discrete or quantized amount of energy, with the energies separating successively higher energy orbitals being different but also discrete. only when the energy of radiation interacting with an atom exactly matches the gap between two energy levels of the atom will an absorption (or emission) event occur. not surprisingly, these energy differences are unique to an individual element, and thus can be used to identify that element. atomic spectroscopy is based on quantized changes in atomic energy that follow the absorption (or emission) of light. in absorption, the energy of the atom increases as an electron is promoted from an orbital of lower energy (the ground state) to one of higher energy (the excited state). in this process, light of the appropriate frequency, , (or wavelength, ) is absorbed according to eq. 1, where e represents the difference in energy (in joules) between the excited and ground states, h is planck's constant (h = 6.626 × 10-34 j s), and c is the speed of light in a vacuum (c = 2.998 × 108 m/s).