Atomic Theory

Question 1

Hunds Rule

Answer 1

For degenerate orbitals, the lowest energy is attained when the number of electrons with the same spin is maximised.

Question 2

Degenerate

Answer 2

Orbitals with the same energy

Question 3

Aufbau principle

Answer 3

Each electron occupies the lowest energy orbital possible.

Question 4

Ionisation energy

Answer 4

The minimum energy required to remove an electron from the ground state of a gaseous atom. Energy is put into the atom to remove the electron so is a positive value. How strongly an atom holds onto an electron.

Question 5

Electron Affinity

Answer 5

The energy change that occurs when an electron is added to a gaseous atom or ion. Measures the affinity an atom has for an electron. Energy is released when an electron is added to an atom so energy change is negative.

Question 6

Electronegativity

Answer 6

The ability of an atom in a molecule to attract shared electrons to itself. An atom with high electron affinity and high ionisation energy will attract electrons from other atoms and resist losing it’s own electrons.

Question 7

Dipole

Answer 7

2 equal magnitude but opposite sign charges are separated by distance r.

Question 8

Dipole moment

Answer 8

Quantitative measure of a dipole.

Mu = qr.

Question 9

Formal charge

Answer 9

Valence electrons-lone pair electrons-bonding electrons/2
Choose Lewis structure with;
1. Atoms bearing formal charges closest to zero or
2. Negative charge resides on the most electronegative atom.

Question 10

Quantum numbers

Answer 10

Principal quantum number is n
Second quantum number is l (angular momentum) l=n-1
Third quantum number is Ml (magnetic) Ml=[-l,l]
Fourth quantum number is Ms (spin) Ms=+1/2, -1/2

Question 11

Pauli exclusion principle

Answer 11

An atomic orbital can hold a max of 2 electrons but with opposite spin. Unique set of 4 quantum numbers.