3.1.1 periodicity

Question 1

what happens to the atomic radius across a given period?

Answer 1

it decreases

Question 2

why does the atomic radius decrease across a given period?

Answer 2

the nuclear charge increases by +1 each so as it increases, the nucleus has a greater attraction for the electrons pulling them in slightly

Question 3

definition of the first ionisation energy

Answer 3

the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive 1+ ions

Question 4

factors affecting ionisation energy

Answer 4

• atomic radius
• electron shielding
• nuclear charge

Question 5

how does atomic radius affect ionisation energy

Answer 5

• the greater the distance between nucleus and outer electrons, the less nuclear attraction

= decreased ionisation energy

Question 6

how does nuclear charge affect ionisation energy

Answer 6

• the more protons in the nucleus, the greater the attraction between nucleus and outer electrons
  =increased ionisation energy

Question 7

how does electron shielding affect ionisation energy

Answer 7

• shielding effect reduces attraction between nucleus and outer electrons as inner shell e- repel outer shell e-

more shielding = decreased ionisation energy

Question 8

what is the trend in 1st ionisation energy down a group?

Answer 8

first ionisation energy decreases down a group

Question 9

explain the trend in 1st ionisation energy down a group

Answer 9

it decreases because:
- more shells so shielding increases
- atomic radius increases
therefore nuclear attraction decreases

Question 10

what is the trend in 1st ionisation energy across a period?

Answer 10

first ionisation energy increases across a period

Question 11

explain the reason for the trend in ionisation energy across a period

Answer 11

it increases because:
- atomic radius decreases
- nuclear charge increases (more protons in nucleus)
therefore nuclear attraction increases