Chapter 7

Question 1

What is ionisation?

Answer 1

The removal of one or more electrons to become an ion
Endothermic reaction -> requires energy

Question 2

Definition of first ionisation energy & second ionisation energy?

Answer 2

1st = energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous +1 ions
2nd = energy needed to remove 1 electron from each ion in 1 mole of gaseous 1+ ions to form to form 1 mole of gaseous 2+ ions

Question 3

Formula for first ionisation of O?

Answer 3

O (g) -> O^+ (g) +e-

Question 4

Which ionisation energy is larger?

Answer 4

The higher ionisation energy as the nuclear attraction on the electron is greater so it is harder to lose an electron so requires more energy

Question 5

Which factors affect ionisation energy?

Answer 5

1) atomic radius (most affects)
2) nuclear charge
3) electron shielding

Question 6

How does atomic radius affect ionisation energy?

Answer 6

Greater distance between nucleus and outer electrons = weaker nuclear attraction so the easier it is to remove an outer electron so the ionisation energy is lower

Question 7

How does nuclear charge affect ionisation energy?

Answer 7

The more protons in the nucleus = stronger attraction between nucleus and outer electrons so it is harder to remove an outer electron = higher ionisation energy

Question 8

What is electron shielding?

Answer 8

The repulsion between the inner shell electrons and the outer shell electrons

Question 9

How does electron shielding affect ionisation energy?

Answer 9

More electron shells an atom has = greater shielding effect which reduces the attraction between the nucleus and outer electrons so ionisation energy lowers

Question 10

What are the predictions that can be made from knowing the ionisation energy?

Answer 10

• number of electrons in the outer shell
• group of element in the periodic table
• identity of an element

Question 11

What are the exceptions for ionisation energy?

Answer 11

1) electron in p orbital is easier to remove an electron from as 3s has higher energy than 3p. Therefore Al which is further across in a period has a lower ionisation energy than Mg (Be to B)
2) an paired electron is easier to remove than a paired electron in p orbital as there is more repulsion between the paired electrons (G2 -> G13) & (G15 -> G16)