Ionisation Energy

Question 1

Define Ionisation Energy

Answer 1

energy required to remove one mole of of electrons from one mole of atoms in the gaseous state

Question 2

What is the unit for ionisation energy?

Answer 2

kJmol-1

Question 3

What is first ionisation energy?

Answer 3

least energy required to remove an electron form a neutral atom

Question 4

What is second ionisation energy?

Answer 4

energy required to remove an electron from a +1 ion

Question 5

What is third ionisation energy?

Answer 5

energy required to remove an electron from a +2 ion

Question 6

Which equation show successive ionisation energies?

Answer 6

1st : X(g) -> X+(g) + e-
2nd : X+(g) -> X2+(g) + e-
3rd : X2+(g) -> X3+(g) + e-

Question 7

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

Answer 7

generally increases because nuclear charge is increasing

Question 8

What is different about the ionisation energies of magnesium and aluminium?

Answer 8

ionisation energy decreases - aluminiums outer electron in 3p orbital whereas magnesium in 3s orbital - less energy to remove from slightly higher 3p orbital

Question 9

Why does ionisation energy decrease between phosphorous and sulfur despite the increase in the nuclear charge?

Answer 9

phosphorous- electrons fill singly in 3p orbital
sulfur- one 3p orbital contains electron pair- this creates repulsion- easier to remove electron

Question 10

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

Answer 10

ionisation energy decreases
outer electron in main energy level that continue sto get further from nucleus

Question 11

Why is ionisation energy unaffected by increased nuclear charge down a group?

Answer 11

shielding by inner electrons reduces the effect of nuclear charge