Atomic Theory 7

What is first ionisation energy

Minimum energy needed to remove the most loosely bound electron from one mole of isolated neutral gaseous atoms in ground state

What is the unit of ionisation energy

kJ mol^-1

Write the first ionisation energy equation

X_(g) => X⁺_(g) + e^-

What state must atoms be in for first ionisation energy

Gaseous state

What does ground state mean

Lowest energy state

What does isolated atom mean

Atom not bonded or interacting with other atoms

What is second ionisation energy

Minimum energy needed to remove an electron from one mole of gaseous X⁺ ions

Write the second ionisation energy equation

X⁺_(g) -> X²⁺_(g) + e^-

Why is second ionisation energy higher than first

Electron is removed from a positive ion

What happens to successive ionisation energies

They increase

Why do successive ionisation energies increase

Remaining electrons feel stronger nuclear attraction

What does a large jump in successive ionisation energy show

A new inner energy level is being entered

What does first ionisation energy generally do across a period

It increases

Why does ionisation energy increase across a period

Nuclear charge increases and shielding stays similar

What happens to atomic radius across a period

It decreases

Why does smaller radius increase ionisation energy

Outer electron is closer to the nucleus

What does first ionisation energy generally do down a group

It decreases

Why does ionisation energy decrease down a group

Atomic radius and shielding increase

What causes increased shielding down a group

Extra inner shells

What is screening effect

Inner electrons reduce nuclear attraction for outer electrons

What is nuclear charge

Positive charge of the nucleus due to protons

Which group has low first ionisation energies

Group 1

Why do Group 1 metals have low first ionisation energies

They have one outer electron which is easily lost

Which group has high first ionisation energies

Noble gases

Why do noble gases have high first ionisation energies

They have stable full outer shells

What sublevel arrangement is most stable

A full sublevel

What is atomic (covalent) radius

Half the distance between nuclei of two identical atoms joined by a single covalent bond

What does low first ionisation energy suggest

Atom loses electrons easily