periodicity

Question 1

what is periodicity?

Answer 1

showing repeating trends in physical and chemical properties

Question 2

what are groups in the periodic table?

Answer 2

elements that have similar chemical properties

Question 3

what is the 1st ionisation energy?

Answer 3

the energy required to remove 1 e- mole from 1 mole of gaseous atoms

Question 4

what are the trends in ionisation energies?

Answer 4

1. the ionisation energy increases down the group

2. ionisation energies are higher in period 3 than 2

Question 5

why is the ionisation energy lower in Si than Al?

Answer 5

silicon has an extra shell so is further from the nucleus

Question 6

what are the factors for strength of ionisation energy?

Answer 6

1. proton no.
2. electron shielding
3. distance to the nucleus

Question 7

what is metallic bonding?

Answer 7

the strong electrostatic attraction between cations and delocalised electrons

Question 8

what are giant covalent structures?

Answer 8

network of atoms joined by covalent bonds

very strong bonds such as in graphite, diamond and graphene

Question 9

what properties do giant metallic structures have?

Answer 9

1. high BP due to strong electrostatic attraction
2. conductor due to delocalised electrons
3. metals BY THEMSELF are insoluble in water

Question 10

what properties do giant covalent covalent structures have?

Answer 10

1. high BP due to strong covalent bonds
2. diamond doesn’t conduct but graphene and graphite do
3. insoluble

Question 11

why is there variation in MP across periods 2 & 3?

Answer 11

1. MP increases group 1-14
2. sharp decrease between group 14 and 15
3. low from 15-18
   this is due to the first 14 being giant structures
   the others are simple