Key definitions

Question 1

Relative atomic mass

Answer 1

The weighted mean mass of an atom compared to 1/12 of the mass of a carbon-12 atom

Question 2

Orbital

Answer 2

A region within an atom that can hold up to 2 electrons with opposite spins

Question 3

Aufbau principle

Answer 3

Lower energy level orbitals must be filled before orbitals at a higher energy level

Question 4

Atomic radius

Answer 4

The distance from the nucleus to the boundary of the electron cloud

Question 5

1st ionisation energy

Answer 5

The energy required to remove 1 mole of the most loosely held electrons from 1 mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of +1

Question 6

Hund’s rule

Answer 6

It states that electrons will occupy the orbitals singly before pairing takes place