3.1 periodicity

Question 1

define: first ionisation energy

Answer 1

value of energy required to convert one mole of gaseous atoms into one mole of positively charged gaseous ions

Question 2

trend of first ionisation energies across the groups

Answer 2

Question 3

trend of first ionisation energy across a period + why

Answer 3

increase. nuclear charge increases, the shielding stays the same. nuclear attraction increases as atomic radius decreases = more energy needed to remove first e-

Question 4

trend of ionisation energy down a group

Answer 4

decrease. number of energy shells and shielding increases so atomic radius increases = the outer electron is easier to remove.

Question 5

why is there a drop in first ionisation energy between group 2 and 3

Answer 5

2s sub-shell gets filled up and the 2p sub-shell is started. the 2p sub-shell in B has a higher energy than the 2s sub-shell in Be

Question 6

why is there a drop in first ionisation energy between group 5 and 6

Answer 6

pairing of electrons, the pairing makes the 8th electron slightly easier to remove due to the repulsion between the paired electrons in the p-orbital.

Question 7

why do the physical and chemical properties vary across period 3

Answer 7

there is a decrease in atomic radius, an increase in first ionisation energy

Question 8

properties of giant metallic lattice

Answer 8

• conduct electricity and heat
• high m.p and b.p

Question 9

properties of diamond

Answer 9

*4 C-C bonds
* lattice structure
* does not conduct
* tetrahedral
* high m.p and b.p
* insoluble

Question 10

properties of graphite

Answer 10

• 3 C-C bonds
• soft layer structure so they can slide over eachother
• conducts electricity as free e’ carry charge
• high m.p and b.p
• insoluble

Question 11

properties of graphene

Answer 11

• 3 C-C bonds
• hard layer structure
• does conduct electricity
• used in circuits

Question 12

silicon dioxide properties

Answer 12

• SAND
• giant covalent lattice
• bonded by strong covalent bonds
• high m.p and b.p
• does not conduct

Question 13

what structure do group 1-3 elements have

Answer 13

giant metallic

Question 14

what structure do group 4 elements have

Answer 14

giant covalent

Question 15

trend in melting and boiling points in period 2

Answer 15

increase until C as giant structures, decrease from N to Ne as simple molecules

Question 16

trend in melting and boiling points in period 3

Answer 16

increase until Si as giant structures, decrease until Ar as simple molecules

Question 17

what is metallic bonding

Answer 17

positive ions in a sea of delocalised electrons leading to strong electrostatic attraction between the cations and electrons

Question 18

general equation to show first ionisation energy

Answer 18