AQA Chemistry A Level Periodicity Summary Notes.

Periodicity Periodicity is the study of trends of the properties
within the periodic table across a period, repeated
down each row. These trends are often linked to the
electronic configuration of an element.

Atomic radius Ionisation energy




:☒!ʰ☆¥ ¥B•qgo⇐j•a*'.j•BMEG☒?Mdk⇐Bq-F.•*gB⑤k
→
i



First ionisation energy is the energy required to
Decreases across a period remove one mole of electrons from one mole of
Nuclear charge increases gaseous atoms
Shielding stays similar
Increases across a period
Increased attraction between
Nuclear charge increases
nucleus and electron
Shielding stays similar
Increases down a group
Decreases down a group
Electron shells added
Electron shells are added
More shielding Shielding increases
Reducing nuclear attraction
Reduces attraction between nucleus and
First ionisation between Mg and Al: electrons
Decreases
Mg loses electron from 3s orbital, Al loses electron from 3p orbital
3p sub level is a higher energy level
Requires less energy to remove the election



Sample
First ionisation energy between P and S: Element with highest ionisation energy:
Decreases Argon
Paired electron in 3p orbital Largest nuclear charge
Electrons repel Same shielding