Metals

Question 1

Way in which metal is used

Answer 1

determined by its physical and chemical properties

Question 2

Metals can be modified in 3 ways

Answer 2

Alloy production
Heat treatment
Coating

Question 3

Alloys

Answer 3

Metals are mixed with small amounts of another substance, usually a metal ot carbon
The substances used are melted, mixed and then allowed to cool, creating an alloy
not a substance

Question 4

Properties of alloys

Answer 4

Harder, less malleable and melt at low temps
- because atoms of diff. sizes do not pack in the same way as main metal and don’t allow the lattice to shift and bend. disruption of regular metallic lattice accounts for low melting point
Poor electrical conductors
-delocalised electrons have restricted movement due to close packing of different sized particles

Question 5

Substitutional alloy

Answer 5

made up of elements with similar chemical properties and atoms of similar size to main metal
metal cations are attracted to sea of delocalised electrons so lattice is strongly bonded

Question 6

Interstitial alloy

Answer 6

An alloy in which a small proportion of an element with atoms of small atomic radius is added to a metal.

Question 7

Crystals of metal

Answer 7

region in a solid where particles are arranged in a regular way
continuous regular arrangement of cations surrounded by delocalised electrons
malleability and brittleness depend on size and arrangement of crystals
generally, smaller crystals result in a harder, more brittle metal (less free movement of layers of cation over each other)

Question 8

Heat treatment

Answer 8

When metals are heated above a critical temperature, individual crystals merge.
when the metal is allowed to cool, the crystals reform
rate of cooling determines how large the new crystal will be

Question 9

Quenching

Answer 9

Faster cooling

leads to smaller crystals

Question 10

Annealing

Answer 10

allows more time for crystals to grow larger

Question 11

Metallic nano materials

Answer 11

metal atoms arranged to make nano sized structures

particles, rods, wires

Question 12

Properties metallic nano materials

Answer 12

different to bulk sample of same metal
because they have a high sa:v ratio compared to bulk size of similar volume
When size of metal crystal decrease, they have too few electrons to amount to a sea of delocalised electrons. Thus, they have different
-optical properties, electrical conductivity, thermal conductivity, metallic lustre