Seneca - Transition Metals Flashcards
What is a usage of the high density of transition metals and how do they relate to alkalis in terms of density?
Transition metals have more mass for the same volume than alkali metals.
The high density makes transition metals useful in construction.
Strength and hardness of transition metals compared to alkali metals
Transition metals are stronger and harder than alkali metals.
Transition metals M.P compared to alkali metals
Transition metals have higher melting points than alkali metals.E.g. Iron’s melting point is 1,583°C, whereas sodium’s is about 98°C.High melting points make transition metals useful for cooking equipment.
How does the reactivity of transition metals compare with alkali metals ?
Transition metals are less reactive than alkali metals.E.g. Iron takes weeks to rust when in contact with oxygen and water, whereas sodium does this in a few seconds.
Special usage of transition metals- charges
Can form ions with different POSITIVE charges
Special usage of transition metals - colour
Can form different colour compounds
Special usage of transition metals - catalysts
For example:
Iron (Fe) is the catalyst used in the Haber process, which results in the production of ammonia.
Platinum (Pt) and rhodium (Rh) are used in catalytic converters in cars.
Special usage of transition metals - catalysts
For example:
Iron (Fe) is the catalyst used in the Haber process, which results in the production of ammonia.
Platinum (Pt) and rhodium (Rh) are used in catalytic converters in cars.
Rusting reaction
Iron + oxygen + water → hydrated iron(III) oxide.
Rusting experiment with iron nail.
Take a boiling tube and put an iron nail inside under three different sets of conditions and see if it rusts:
Only water (oil stops air from water)- no rust.
Only air - no rust.
Water and air - rust
Methods of rust prevention- coatings
We can prevent corrosion by applying a coating that acts as a barrier, such as greasing, painting or electroplating.
E.g. Aluminium has an oxide coating that protects the metal from further corrosion by preventing the metal’s surface coming into contact with oxygen and water.
A disadvantage is that any damage to the coating will lead to the metal becoming exposed and so corrosion will take place.
Method if rust prevention - galvanising (I know sacrificial protection).
Galvanising is a hybrid of coatings and the sacrificial method.The metal that needs protecting is sprayed with a more reactive metal. This initially acts as a coating.If the more reactive metal is damaged, it will continue to protect as a sacrificial metal.
Electroplating
Electrolysis can be used to electroplate objects, normally other metals.We can use this process to coat a cheaper metal with a more expensive one. This gives the cheaper metal the appearance of the more expensive metal, which could be gold or silver. This gives us the option of buying cheaper jewellery.The process works by placing the metal to be electroplated at the negative electrode (cathode) and the coating metal at the positive electrode (anode).Metals are good conductors of electricity. This is why we use copper, steel (alloy of iron) and aluminium for electrical cables.The cables are surrounded by an insulator (does not conduct electricity), such as plastic for safety.
How can we change a metals properties ?
An alloy is a metal that is mixed with other elements. By adding these other elements, we can change a metal’s properties.
Properties and uses of alluminium
A key feature of aluminium alloys is their low density, which makes them suitable for use in manufacturing planes.Other uses include armour plating for military vehicles.
