A2 Ionisation energy and periodicity

Question 1

What is the definition for first ionisation energy?

Answer 1

Ionisation energy is the amount of energy needed to remove a mole of electrons from a mole of atoms, in the gaseous state.

Question 2

When an atom is ionised where is the first electron removed from?

Answer 2

The outer most shell

Question 3

What is the unit for ionisation energy?

Answer 3

kJmol-1

Question 4

What do the periods tell you about an atom and how does in change down a group?

Answer 4

Periods tell you the number of shells; increasing down a group.

Question 5

The number of shells increases down the group. How does this affect shielding?

Answer 5

Shielding increases

Question 6

How does the number of shells affect electrostatic attraction?

Answer 6

More shells, more shielding, less electrostatic attraction between the nucleus and the outer electrons.
Less shells, less shielding, more electrostatic attraction between the nucleus and the outer electrons.

Question 7

What is shielding?

Answer 7

The blocking of outermost shell electron attraction by the nucleus, due to the presence of inner-shell.

Question 8

How is the nuclear charge changing across a period?

Answer 8

Increasing nuclear charge

Question 9

Which has more shielding, Boron or Aluminium?

Answer 9

Aluminium as it has more shells.

Question 10

What is happening to the radius (size) across a period?

Answer 10

Shielding is the same (same number of shells), the nuclear charge is increasing (amount of protons), stronger electrostatic attraction between the nucleus and the outermost electrons, radius is decreasing.

Question 11

What is happening to the radius (size) down a group?

Answer 11

Shielding increases (more shells), less attraction between the nucleus and the outer electrons, radius increases.

Question 12

What is happening to the IE across a period?

Answer 12

Shielding is the same (same number of shells), the nuclear charge is increasing (amount of protons), stronger electrostatic attraction between the nucleus and the outermost electrons, more energy is required to remove the outermost electron.

Question 13

What is happening to the IE down a group?

Answer 13

Shielding increases (more shells), less electrostatic attraction between the nucleus and the outermost electron, less energy to remove the uttermost electron. IE decreases.

Question 14

Why does the first ionisation energy decrease down a group?

Answer 14

Shielding increases (more shells), less electrostatic attraction between the nucleus and the outermost electron, less energy to remove the outermost electron.

Question 15

What is the trend in IE from Li to Ne?

Answer 15

Shielding is the same (same number of shells), the nuclear charge is increasing (amount of protons), stronger electrostatic attraction between the nucleus and the outermost electrons, smaller atomic radius.

Question 16

Which is the smaller, Na or Mg?

Answer 16

Mg.
Same number of shells, same shielding.
Mg has more protons so
the outer electrons are more strongly attracted to the nucleus

Question 17

The second electron of K is removed from an ion that already has a positive charge. What will this mean for IE?

Answer 17

The second ionisation would be higher.

Question 18

Which has a greater first IE, Be or Mg?

Answer 18

Be
Be has less shielding than Mg, stronger electrostatic attraction between the nucleus and the outermost electrons, more energy is required to remove the outermost electron.

Question 19

Why is the second ionisation energy of C higher than the first?

Answer 19

The second electron is removed from an ion that already has a positive charge.

Question 20

From Na to Ar the ionisation energy is increasing. Why?

Answer 20

Shielding is the same (same number of shells), the nuclear charge is increasing (amount of protons), stronger electrostatic attraction between the nucleus and the outermost electrons, more energy is required to remove the outermost electron.

Question 21

The electrostatic attraction changes with changing shielding. Why?

Answer 21

More shells, more shielding, less electrostatic attraction between the nucleus and the outer electrons.
Less shells, less shielding, more electrostatic attraction between the nucleus and the outer electrons.

Question 22

Why does the first IE increase across a period?

Answer 22

Shielding is the same (same number of shells), the nuclear charge is increasing (amount of protons), stronger electrostatic attraction between the nucleus and the outermost electrons, more energy is required to remove the outermost electron.