Periodicity

Question 1

what happens across a period

Answer 1

electrons are added into the same shell
shielding stays the same
number of protons increases
= attraction between nucleus and outer electrons increases

Question 2

what happens to the atomic radius across a period

Answer 2

decreases

Question 3

what happens to the first ionisation energy across a period

Answer 3

increases

Question 4

what happens to the electronegativity across a period

Answer 4

increases

Question 5

what happens down a group

Answer 5

-each successive element has an extra shell of electrons
- shielding effect of inner electron shells increases
- attraction between nucleus and outer electrons decrease

Question 6

what happens to the atomic radius down the group

Answer 6

increases

Question 7

what happens to the first ionisation energy down the group

Answer 7

decreases

Question 8

what happens to the electronegativity down the group

Answer 8

decreases

Question 9

melting points of period 3 elements : sodium, magnesium, aluminium

Answer 9

-melting point increases
- more delocalised electrons
- + charge on ions increases
- +ions get smaller
metallic attraction between + ions and delocalised electrons
structure= metallic giant lattice

Question 10

melting points of period 3 elements : silicon

Answer 10

• high melting point
  -strong covalent bonds which need to be broken - requires a lot of energy
• macromolecular
• giant covalent lattice structure
• covalent bonds

Question 11

melting points of period 3 elements : phosphorus, sulphur, chlorine

Answer 11

structure = covalent molecular
- weak van der Waal forces between molecules
- bigger molecules = more electrons = stronger van der Waal forces