Question

Which is the correct order of increasing energy of the listed orbitals in the atom of titanium?
(Atomic no. Z=22)

• A. $3s<3p<3d<4s$
• B. $3s<3p<4s<3d$
• C. $3s<4s<3p<3d$
• D. $4s<3s<3p<3d$

Answer 1

The correct option is B $3s<3p<4s<3d$

$n+l$ value:
$3s=3+0=33p=3+1=44s=4+0=43d=3+2=5$
Higher the $n+l$ value, higher is the energy
If $n+l$ value is same, then higher value of $n$ will have more energy.
The filling of electrons in the orbitals is in accordance with Aufbau’s rule.
The correct order of increasing energy of the listed orbitals in the atom of titanium is
$3s<3p<4s<3d$.
The energy of 4s orbital is lower than the energy of 3d orbital.
Due to this, 4s orbital is filled first followed by 3d orbital.