2.3 - metallic

Question 1

define metallic bonding

Answer 1

electrostatic attraction between metal cations and a sea of delocalized electrons

Question 2

degree of electron delocalization and electronegativity relation

Answer 2

inversely proportional so metallic properties increase down groups and decrease across periods, opposite to electronegativty

Question 3

properties of metallic structures (4)

Answer 3

• good electrical conductors
• good thermal conductors
• malleable
• ductile

Question 4

why are metals used to make cookware

Answer 4

• thermal conductivity
• when heated the vibrations increase and are passed along to other cations due to their closely packed arrangemenet
• energy also transferred to the surrounding electrons
• mobile electrons pass this energy to other parts of the lattice

Question 5

cause of electrical resistance + how it can increase

Answer 5

as thermal energy increases, ions vibrate more due to collisions
some kinetic energy is convereted to heat which causes electrical resistance which increases with temperature

Question 6

how can resistance decrease in a metal

Answer 6

lower temp -> lower frequency of collisions -> electrons move in a more direct path with low resistance

Question 7

superconductors

Answer 7

materials that offer no resistance to electric current below a certain ‘critical’ temperature

Question 8

malleability + use

Answer 8

ability to be pressed or pounded into diff shapes

metals can be used in aeroplanes / needles al;l sizes

Question 9

metallic bonding direction

Answer 9

• non directional
• when a force is applied layers of cations canm slide past each other without breaking the electrostatic force of attraction
• new shape

Question 10

use of non directional bonding

Answer 10

change in shape like aluminium foil used to wrap food

Question 11

strength of metallic bonds (3)

Answer 11

• inverse to ionic radius
• direct to ionic charge
• direct to electron density of delocalised electrons (greater electrostatic forces)

Question 12

ductility + use

Answer 12

the ability to be stretched into wires
coupled with electrical conducitvity this is the reason wires are industrially produced

Question 13

melting and boiling points trend down the grp (mention ionic radius)

(3)

Answer 13

• decrease down the group as ionic radius increases
• greater distance between cations and delocalized electrons
• weaker electrostatic forces of attraction

Question 14

melting and boiling point across period

Answer 14

• increases
• ionic radius decreases
• ionic charge increases
• more delocalized electrons per ion

Question 15

properties of transition elements (6)

Answer 15

• hard
• strong
• dense
• variable oxidation states
• catalytic properties
• coloured compounds