<Li> Each g subshell holds at most 18 electrons </Li> <P> Therefore, the K shell, which contains only an s subshell, can hold up to 2 electrons; the L shell, which contains an s and a p, can hold up to 2 + 6 = 8 electrons, and so forth; in general, the nth shell can hold up to 2n electrons . </P> <P> Although that formula gives the maximum in principle, in fact that maximum is only achieved (by known elements) for the first four shells (K, L, M, N). No known element has more than 32 electrons in any one shell . This is because the subshells are filled according to the Aufbau principle . The first elements to have more than 32 electrons in one shell would belong to the g - block of period 8 of the periodic table . These elements would have some electrons in their 5g subshell and thus have more than 32 electrons in the O shell (fifth principal shell). </P> <P> The valence shell is the outermost shell of an atom . Valence electrons in non-transition metal elements reside in this shell . Such elements with complete valence shells (noble gases) are the most chemically non-reactive, while those with only one electron in their valence shells (alkali metals) or just missing one electron from having a complete shell (halogens) are the most reactive . </P>

The maximum number of electrons that can be held in the k and l energy levels are