Periodicity

Question 1

Describe the trend in ionisation energy across a period

Answer 1

IE increases across a period because there is a greater charge on the nucleus, causing a greater attraction between the nucleus and electrons with no extra shielding to compensate.

Question 2

Describe the trend in ionisation energy down a group

Answer 2

IE decreases down a period because there is increased shielding, causing a lesser effective charge on the nucleus and a lesser attraction between the nucleus and electrons.

Question 3

Describe the trend in atomic radius down a group

Answer 3

Atomic radius increases down a group because more energy levels are added

Question 4

Describe the trend in atomic radius across a period

Answer 4

Atomic radius decreases across a period because the increased nuclear charge holds the electrons more tightly, drawing them in.

Question 5

Describe the trend in reactivity down groups 1&2

Answer 5

Ionisation energy decreases meaning they are more easily oxidised and become stronger reducing agents

Question 6

Describe the trend in reactivity down group 7

Answer 6

Decreases down the group because they are more easily reduced and become stronger oxidation agents

Question 7

What is electronegativity

Answer 7

A measure of the tendency of an atom to attract a bonding pair of electrons

Question 8

Describe the trend in electronegativity across a period

Answer 8

Increase in electronegativity due to increased nuclear charge and no additional shielding

Question 9

Describe the trend in electronegativity down a period

Answer 9

Decrease in electronegativity due to increased shielding causing a lower effective charge