Question

The energy of the electron depends on the size of the......................
A) Orbit
B) Orbital
C) Both A and B
D) None of the above

Answer 1

If we are given the atomic number of any element and told us to write the electronic configuration in the ground state we fill the orbitals according to the ‘Aufbau Principle’ which say to fill the orbitals in the order of their increasing energies. In other words to follow the (n+l) rule.

Complete Step by step answer: We know that atoms contain protons, neutrons and electrons.
Protons and neutrons are concentrated at the centre of the atom called as nucleus and electrons are moving around the nucleus in various orbits called as shells and each shell consists of sub shells.
-(n+l) rule: where n represents the principal quantum number and l represents the azimuthal quantum number or orbital angular momentum.
Principle quantum number (n) determines the size and energy of the orbit and also indicates the number of shells. Which takes up the only positive integer values 1,2,3,4...... For the shell K, L, M, N......respectively.
-Azimuthal quantum number (l) indicates shape and energy of the orbital and it takes up 0 to (n-1) value. If l = 0,1,2,3...... The notations used s, p, d, f..... respectively
Using (n+l) rule the orbitals are arranged as 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d.......
Therefore the energy of the electron depends on both orbit and orbital.

Hence the correct option is C.

Note: It can be noted that 3d has higher energy than 4s. We can check this using the (n+l) rule.
For 3d, n = 3 and l = 2
$\left( {{\text{n + l}}} \right) = {\text{ 3 + 2 = 5}}$
For 4s, n = 4 and l = 0
$\left( {{\text{n + l}}} \right) = {\text{ 4 + 0 = 4}}$
Since 5 is greater than 4, 3d has higher energy than 4s.