C13- Transition Metals

Question 1

What’s a transition metal

Answer 1

They are elements in the central block of periodic table between groups 2 and 3 - include most metals used for construction, vehicles, jewellery and other everyday uses

Question 2

Tell me the TYPICAL physical properties

Answer 2

Malleable

Ductile - can be stretched out to make thin wires

Good conducters of electricity

Shiny when polished

When compared to aluminium and the metals in groups one and two: they typically have high melting points and high densities

Question 3

Tell me some exceptions of the properties

Answer 3

Mercury is a transition metal and has a high density but is liquid at room temp

Question 4

Tell me about the chemical properties of transition metals

Answer 4

Form coloured compounds

The metals and compounds typically show catalytic activity

Catalysts increase the rate of a reaction without being changed chemically or in mass at the end of a reaction

Eg iron is used as a catalyst to manufacture ammonia in the Haber process

Question 5

When do metal oxides form

Answer 5

When metals react with oxygen in in air and oxidise

More reactive metals oxidise quickly

When metals lose electrons

Question 6

What’s tarnish

Answer 6

Some metals may form a layer of tarnish when they oxidise - this stops oxygen reaching the metals preventing further oxidation

Question 7

What’s corrosion

Answer 7

Happens when a metal continues to oxidise so a metal becomes weaker over time

Question 8

What’s rusting

Answer 8

It’s the corrosion of iron or steel with reacts with oxygen and water

Iron + oxygen + wager = hydrated iron (III) oxide - it looks like dust - flakes fall off to expose more metal to air and continues to weaken the iron

Question 9

How can rusting be prevented

Answer 9

Keeping metal in an unreactive atmosphere of nitrogen or argon

Or if water Is kept away using a desiccant powder that absorbs water vapour

Or painting , coating with plastic, oiling and greasing

Question 10

Tell me about sacrificial protection

Answer 10

Method of rust prevention that doesn’t rely of keeping air or water away

A piece of magnesium or zinc or since is attached to an iron or steel object which oxidises more easily so oxygen reacts with them instead and protection continues until the sacrificial metal corrodes away

The more reactive a metal - the more reactive a metal loses its electrons and more easily oxidised

Question 11

What’s electroplating

Answer 11

It coasts the surface of one metal with a thin layer of another - less reactive or corrosion resistant

Question 12

What do you need to carry out an electroplating

Answer 12

An anode made from the plating material

An electrolyte - solution containing ions of the plating metals

Cathode which is the metal object itself

Question 13

What’s a d.c

Answer 13

Direct current which flows through the electrodes and the electrolyte

Question 14

How does the electroplating of a copper ring with silver work

Answer 14

A d.c flows through electrodes and electrolytes - silver jons in electrolyte move to cathode (copper ring) and gain electro jons and are deposited as silver ions, at the silver anode, silver atoms lose electrons to become silver ions, which go into the electrolyte, the longer the current flows, the thicker the silver layer on the ring becomes

Question 15

What’s galvanising

Answer 15

Coating iron and steel objects with since - improves corrosion resistance by stopping water reaching the iron or steel and acting as a sacrificial metal - and sacrificial protection can continue even if zone layer is damaged

Question 16

How is galvanising carried out

Answer 16

Using electroplating or dipping the object In molten zinc

Question 17

Tell me about tin plating

Answer 17

Food cans inner surface is protected from rusting by electroplating with Tin which doesn’t react with air or water at room temp - so it can reach the steal but of its damaged the steel can rust faster because iron is more reactive than tin - so iron acts as a sacrificial metal

Question 18

What’s an alloy

Answer 18

A mixture of a metal element with one or more other elements, usually metals

Question 19

What are alloy steels

Answer 19

They are made by deliberately adding other elements to iron to add properties by varying their composition

Question 20

Tell me about stainless steel

Answer 20

Resists rusting and contains chromium which reacts with oxygen in the air and water reaching the metal below - but thing enough to be transparent but if it’s scratched more chromium reacts to replace the layer

Add manganese for strength and maintain malleability

Question 21

The greater the carbon content of steel…..

Answer 21

The stronger and harder it is

Question 22

Why can stronger steels be bad

Answer 22

Can be more difficult to press into shape but used to produce strong but relatively light weight car bodies

Question 23

Why are alloys often stronger than pure metals

Answer 23

In solid, pure metal atoms are the same size so layers can be pushed past each other if enough force
- so they are malleable and ductile

In an alloy - the atoms of other elements present may be different sizes - distort the regular structure so alloys are stronger but still are usually malleable and ductile

Question 24

What does the use of a metal or alloy depend on

Answer 24

Chemical properties such as resistance to corrosion

Physical properties such as density

Depends on the use

Question 25

Tell me about magnalium

Answer 25

Alloy of aluminium 95% and 5% magnesium used for aircraft parts and scientific instruments its less dense and almost 4 times stronger than aluminium alone - so it can be used to manufacture strong but light weight parts