Question

Arrange the following orbitals in the order in which they are filled with electrons.
$6s,5d,6p,7s,5f$

• A. $6s<5d<6p<7s<5f$
• B. $6s<6d<5d<5f<7s$
• C. $6d<5f<6s<6p<7s$
• D. $6s<7s<5d<5f<6p$

Answer 1

Answer: (A)

$6s<5d<6p<7s<5f$

According to the Aufbau principle, electrons are filled in order of their increasing energies. Thus the orbital with the least energy is filled first.

The correct sequence therefore is; $6s<5d<6p<7s<5f$.