sc13, transition metals, alloys, corrosion (paper 1) Flashcards
in what groups are transition metals found in
between 2 and 3
give properties of transition metals
- high melting points (except mercury)
- high density
- stronger + harder than group 1 and 2, so they are more suitable as construction metals
- form coloured compounds
transition metals have catalytic activity, what does this mean
- increase the rate of a chemical reaction
- without altering the products of a reaction
- without changing chemically
- without changing in mass at the end of reaction
suggest two reasons why a metal object may be electropated
- improve it’s appearance
- improve its resistance to corrosion
what happens in the process of electropating a metal object
- a thin layer of an unreactive metal is deposited on the surface of the metal object
- (e.g silver, nickel, gold)
- keeping air and water out
how can you prevent rusting from oxygen and water
- painting
- using oil or grease
- coating with plastic or another metal
what is name given to the process of coating a metal with another metal
galvanising
what is galvanising
coating a metal with another metal
what happens during galvanising
- the metal is dipped in molten metal or electropated with it
what are the conditions for the chosen metal in galvanising
- more reactive thn iron
- reacts slowly with water
- so it corrodes before the iron/steel
- and prevents air and water reaching the iron beneath (acts as a sacraficial protector)
how can you keep oxygen away from an object
store it in a vacuum cleaner
how can you keep water away from an object
store it in a container with a desiccant
what is a desiccant
absorbs water vapour
what is an alloy
a mixture of a metal with one or more other elements (usually another metal or carbon0
what metal is mixed with pure iron to form an alloy called steel
carbon and other metals