If an atom has twelve electrons, how many electrons are in the n=1 energy level? how many electrons are in the n=2 energy level? how many electrons are in the n=3 energy level?

Magnesium has 12 electronswhich wud mean that in the 1st energy level(n=1) there r 2 electrons, in the 2nd energy level(n=2) there r 8 electrons and in the 3rd energy level(n=3) there r 2 electronsits simpleuse the formula 2n^2 where n= 1,2,3,  

so the electron configuration of Magnesium in 2,8,2or more precisely 1s2, 2s2, 2p6, 3s2

lunar landing mission. apollo 11 was the first manned mission to land on the moon. the first steps by humans on another planetary body were taken by neil armstrong and buzz aldrin on july 20, 1969. the astronauts also returned to earth the first samples from another planetary body.

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