3.2.1 Periodicity

Question 1

what happens to atomic size (radius) across the period?

Answer 1

• atomic radius DECREASES because:
• nuclear charge inc. because no. of protons inc.
• similar shielding
• nuclear attraction on the last shell electron gets stronger so there is a greater pull

Question 2

what happens to atomic radius down the group?

Answer 2

• atomic radius INCREASES because:
• no. of shells inc. so shielding inc.
• nuclear attraction of the last shell electron gets weaker so there is less pull

Question 3

what happens to IE across the period?

Answer 3

IE INCREASES because:
- atomic radius dec. so nuclear charge inc.
- similar shielding
- nuclear attraction on the last shell electron is getting stronger so more energy is needed to remove it

Question 4

what happens to IE down the group?

Answer 4

IE DECREASES because:
- shielding is increasing
- nuclear attraction on the last shell electron is getting weaker so less energy is needed to remove it

Question 5

why does the trend in IE stop between groups 2 and 3? (e.g. Be and B)

Answer 5

In B the electron is removed from 2p subshell which is further away from the nucleus. In Be the electron is removed from the 2s which is closer to the nucleus, so more energy is needed to remove it

Question 6

why does the trend in IE stop between group 5 and 6? (e.g. N and O)

Answer 6

N has a higher IE than O because O has 2 electrons in one of the 2p orbitals which repel, so less energy is needed to remove the outer electron.

Question 7

what happens to electronegativity down the group?

Answer 7

electronegativity DECREASES because:
- size of the atom inc, more shielding
- nuclear attraction on the bonding pair of electrons dec.

Question 8

what happens to electronegativity across the period?

Answer 8

electronegativity INCREASES because:
- size of the atom dec., nuclear charge increases as there are more protons
- shielding is similar so the nuclear attradction on the bonding pair of electrons gets stronger