Ionisation Energy

Question 1

Equation for the first ionisation energy of element X?

Answer 1

X(g) -> X+(g) + e-

Question 2

What are the three factors that determine ionisation energy?

Answer 2

Nuclear charge
Electron shielding
Atomic radius

Question 3

What effect does nuclear charge have on ionisation energy?

Answer 3

Greater the nuclear charge the greater the attractive force on the outer electron so the more difficult it is to remove the electron.

Question 4

What effect does electron shielding have on ionisation energy?

Answer 4

The more inner shells or sub shells there are the smaller the force on the outer electron

Question 5

What effect does atomic radius have on ionisation energy?

Answer 5

The greater the atomic radius the smaller the attractive force on the outer electron because the pull from the nucleus is less effective.

Question 6

What is the general trend in ionisation energy across a period?

Answer 6

Increase- nuclear charge increases but number of shells and so electron shielding stays the same

Question 7

What is the general trend in ionisation energy down a group?

Answer 7

Decrease- outer electron is further from nucleus and has increased shielding from inner electrons

Question 8

What is the definition of ‘molar first ionisation energy’?

Answer 8

The energy required to remove one mole of electrons from one mole of its gaseous atoms.

Question 9

Why do successive ionisation energies increase?

Answer 9

As each electron is removed there is less electron to electron repulsion and each shell is drawn closer to the nucleus. The atomic radius decreases and nuclear attraction increases.

Question 10

What does a large jump in successive ionisation energies show?

Answer 10

That the electron is removed from a new shell that is closer to the nucleus