Periodicity

Question 1

Describe change in atomic radius across 3rd period

Answer 1

Smaller across periods, bigger down groups

Question 2

Explain change in atomic radius across 3rd period

Answer 2

More protons in nucleus (stronger nuclear charge)
Same amount of shielding
Outer electrons in same shell
Stronger attraction between nucleus and outer shell electron so outer shell electrons pulled closer to nucleus

Question 3

Describe trend in ionisation energy across 3rd period

Answer 3

Generally increases across period except between group 2-3 and group 5-6

Question 4

Explain change in ionisation energy across 3rd period

Answer 4

More protons (stronger nuclear charge)
Smaller atomic radius
Same shielding
Therefore stronger attraction between nucleus and outer shell electron so more energy required to lose outer shell electron

Question 5

Why ionisation energy dip between group 2-3?

Answer 5

Group 2: electron lost from s orbital
Group 3: electron lost from p orbital
P orbital higher in energy than s so less additional energy required, so easier to lose electron

Question 6

Why ionisation energy dip between group 5-6?

Answer 6

Group 5: electron lost from singularly occupied orbital
Group 6: electron lost from orbital with 2 electrons
Therefore easier to lose electron from group 6 element as more electron-electron repulsion

Question 7

Electronegativity definition

Answer 7

Power of an atom to attract the 2 electrons in covalent bond

Question 8

Describe trend in electronegativity

Answer 8

Increases across period and up group

Question 9

Explain change in electronegativity across period

Answer 9

More protons in nucleus (stronger nuclear charge)
Smaller atomic radius
So stronger attraction between nucleus and electrons in covalent bond

Question 10

Reason for different melting/boiling points

Answer 10

Different structures; giant covalent highest, then metallic, then simple molecular, monatomic lowest

Question 11

How to determine which metal has higher m.p. / b.p.

Answer 11

Higher if; higher charge, more delocalised electrons, smaller

Question 12

How to determine which simple molecular molecule has higher m.p. / b.p.

Answer 12

Higher if; bigger molecule as more electrons so more Van der Waals’ forces

Question 13

What groups have what orbitals?

Answer 13

Groups 1-2 (+helium and hydrogen) = s orbitals
Transition metals = d orbitals
Groups 3-8 = p orbitals