the atomic number of Al is 13. Atomic number of an element is the number of protons, atomic number is characteristic to the element. the element in its neutral form has an equal number of protons and electrons, hence its neutral
therefore number of electrons in Al is 13
electronic configuration is the order in which electrons are arranged in the respective energy shells and subshells
electronic configuration of Al is 1s² 2s² 2p⁶ 3s² 3p¹
noble gas electron configuration is where you find the noble gas just before Al in order of atomic numberand the noble gas just before Al is Ne with an atomic number of 10.
So replace 1s² 2s² 2p⁶ with [Ne]
then the noble gas electron configuration of Al is [Ne] 3s² 3p¹
