Electrons always fill orbitals in the same order. each s orbital holds 2 electrons, each set of p orbitals holds 6 electrons, each set of d orbitals holds 10 electrons, and each set of f orbitals holds 14 electrons. the order in which orbitals are filled, from first to last, is:

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

to what element does the following electron configuration correspond?

1s22s22p4

a. aluminum: 13 electrons
b. oxygen: 8 electrons
c. boron: 5 electrons