Chemistry Topic 1

Down A Group:

-Nuclear charge increases

-More Quantum shells are added so outermost electron is farther from the nucleus

-Due to added Quantum shells, there is an increased level of electron - electron repulsion (shielding) resulting in a decreased attraction to the nucleus.

Therefore, Ionisation Energy decreases down a group.

Across a period:

-Nuclear Charge increases

-No more quantum shells

-Increased electron - electron repulsion (shielding

Nuclear Charge is more significant. Therefore, Ionisation energy Increases across a period