Chemistry Chapter 1: Atomic Structure and Periodic Trends

Question 1

Principle Quantum Number (n) definition, possible values and role

Answer 1

Defines: The energy level (or shell) of the electron.
Possible Values: Positive integers (
n=1,2,3,…).
Role:
Indicates the size and energy of the orbital.
Higher n values correspond to higher energy levels and larger orbitals.

Question 2

Azimuthal (Angular Momentum) Quantum Number (l) definition, possible values and role

Answer 2

Defines: The shape of the orbital (subshell).

Possible Values: Integers ranging from 0 to (n-1).

l = 0: s-orbital (spherical)
l = 1: p-orbital (dumbbell-shaped)
l = 2: d-orbital (clover-shaped)
l = 3: f-orbital (complex shape)

Role: Describes the orbital’s shape and determines its subshell.

Question 3

Magnetic Quantum Number (ml)

Answer 3

Defines: The orientation of the orbital in space.

Possible Values: Integers ranging from -l to +l, including 0.

Example: If l = 1 (p-orbital), then ml = -1, 0, +1, corresponding to the three p-orbital orientations (px, py, pz).

Role: Specifies the number of orbitals and their orientations within a subshell.

Question 4

Spin Quantum Number (ms)

Answer 4

Defines: The spin of the electron.

Possible Values: +1/2 (spin-up) or -1/2 (spin-down).

Role: Describes the intrinsic angular momentum (spin) of the electron.

Question 5

Hund’s Rule

Answer 5

electrons fill degenerate (two or more orbitals have the same energy level) orbitals singly with parallel spins before pairing up, to minimize electron repulsion and maximize stability.

Question 6

Aufbau’s rule

Answer 6

Electrons fill atomic orbitals in order of increasing energy, starting from the lowest energy level before moving to higher ones.

Question 7

Pauli exclusion principle

Answer 7

states that no two electrons in the same atom can have the same set of all four quantum numbers (n, l, ml, ms), meaning each electron in an atom must occupy a unique quantum state.