Chapter 13 - Transition Metals, Alloys And Corrosion Flashcards
What is an alloy?
An alloy is a mixture of two or more elements, of which at least one is a metal
What are ‘tough steel’ alloys used for? What are the metals names which are often added to make it tuff?
Tungsten and molybdenum are used to make tools
What is steel made from / can be made from? What is steel?
Steel is an alloy of iron with carbon and usually other elements. Steel is mostly made from carbon and iron, but low alloy steel is made with other elements other than carbon, like chromium or nickel to improve the strength of thick sections.
What is stainless steel made from?
A form of steel containing chromium, resistant to tarnishing or rust
What is oxidation in terms of oxygen?
The alkali metals gain oxygen which causes them to dull quickly as they react
What is tarnish?
A thin layer that forms of metals due to oxidation, it stops oxygen reaching the metal like a protection
What is sacrificial protection?
Magnesium or zinc attached to an iron or steel object, they sr more easily a oxidised so protects the metal underneath until it corrodes away so it has to be maintained
What is galvanising?
When iron and steel is coated with zinc to protect it from rusting, acts as a sacrificial metal and is either dipped in molten zinc or electroplated
What is used to protect steel cans?
Tin is used as a sacrificial protection to stop the food being contaminated by rust, so if it is dropped it will break the protection and rust
Where are the transition metals found on the periodic table?
In the blocks between group 1 and group 2 on the periodic table
Name some typical physical properties of transition metals
Hard/tough/strong, solid room temperature ( mercury is the only exception), high melting points, high density, malleable, ductile
Name some typical chemical properties of transition metals
Low reactivity/react slowly, electrical conductors, form coloured compounds, used as catalysts in other reactions
What is a catalyst?
Something that helps speed up a reaction without being used up themselves or a high pressure or temperature being needed
