Question

Part A

How many orbitals are there in the third shell (n=3)?

Express your answer numerically as an integer.

Part B

Show the orbital-filling diagram for N (nitrogen). Stack the subshells in order of energy, with the lowest-energy subshell at the bottom and the highest-energy subshell at the top.

Part C

Show the orbital-filling diagram for S (sulfur). Stack the subshells in order of energy, with the lowest-energy subshell at the bottom and the highest-energy subshell at the top.

Part D

Show the orbital-filling diagram for Br (bromine). Stack the subshells in order of energy, with the lowest-energy subshell at the bottom and the highest-energy subshell at the top.

Answer 1

Concepts and reason

The principle quantum number represents the shell number of the electron present and is indicated by the letter “n”.

The principle quantum number describes the shell energy and the atomic radius of an atom. While writing the electron configuration, electrons are usually represented in atomic orbitals.

Orbital:

An orbital is a region where the finding probability of an electron is the highest in the shell.

Electronic configuration:

Electronic configuration is the representation of electrons in various orbitals present in different shells. This electronic configuration filling in orbitals follows specific laws:

1.Aufbau principle

2.Hund’s rule

3.Pauli’s exclusion rule

Fundamentals

Aufbau principle: In the ground state of an atom, electrons fill in the lowest energy orbitals first. Only after filling the lowest energy level orbital, do the electrons go to higher energy orbitals.

Energy order of the orbitals:

${\rm{1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s}}$

Hund’s rule: Hund’s rule explains electron filling in degenerate levels; all sub level orbitals should be singly occupied before pairing by the electrons.

Pauli’s exclusion rule: Pauli’s exclusion rule describes that the electron pairs do not exist in an atom which have the same quantum numbers.

Atomic model:

Part A

Given shell number is 3. That is, the principle quantum number is 3.

n = 3.

Shell designation is M and has 3 (s, p and d) orbitals in the shell. The p-orbital has 3 degenerate orbitals as ${{\rm{p}}_{\rm{x}}}{\rm{,}}\,{\rm{ }}{{\rm{p}}_{\rm{y}}}\,{\rm{ and }}\,{{\rm{p}}_{\rm{z}}}$ while the d-orbital has 5 degenerate orbitals, namely, ${{\rm{d}}_{{\rm{xy}}}}{\rm{, }}\,{{\rm{d}}_{{\rm{yz}}}}{\rm{,}}\,{\rm{ }}{{\rm{d}}_{{\rm{zx}}}}{\rm{,}}\,{\rm{ }}{{\rm{d}}_{{{\rm{x}}^{\rm{2}}}{\rm{ - }}{{\rm{y}}^{\rm{2}}}}}\,{\rm{ and }}\,{{\rm{d}}_{{{\rm{z}}^{\rm{2}}}}}$ . The s-orbital doesn’t have any degenerate orbitals.

Therefore, the total number of orbitals is 9

Part B

Atomic number of nitrogen is 7

Orbital filling energy diagram:

Part C

Atomic number of sulfur is 16

Orbital filling energy diagram:

Part D

The atomic number of bromine is 35

Orbital filling energy diagram:

Ans: Part A

The total number of orbitals in the third shell is 9

Part B

Orbital filling energy diagram of nitrogen:

Part C

Orbital filling energy diagram of sulfur:

Part D

Orbital filling energy diagram of bromine: