Helium 2 protons, 2 electrons, 2 neutronsCalcium 20 protons, 20 electrons, 20 neutronsAluminum 13 protons, 13 electrons, 14 neutronsI just don't understand how to find out how many electrons are in each energy level.
Helium:2p 2n 2e Calcium:20p 20n 20e Aluminum: 13p 14n 13e Generally the n of electrons are equal to number of protons and are arranged in shellsA shell can contain up to 2n? electrons; where n equals the shell numberEvery shell has 5 subshells s p d f g Their energy levels are not ordered but they are mangled (see image)so He 1s2, Al 1s2+2s2+2p6+3s2+3p1, Ca 1s2+2s2+2p6+3s2+3p6+4s2Al example says 1st shell s subshell has 2 electrons 2nd shell s subshell has 2 electrons 2ns shell p subshell has 6 electrons 3rd shell s subshell has 2 electrons 3rd shell p subshell has 1 electron Total : 13, so 2+8+3 for the 3 shellsRead my proposed source image for more, where you can find the energy levels of first n shellsNote that every dot may have maximum 2 electrons (Pauli)
