Topic 5- Separate Chemistry Flashcards
Where are transition metals found on the periodic table ?
The transition metals are found in the middle of the periodic table. To their left is Group 2 and to their right is Group 3
Relative to the alkali metals, what do transition metals have ?
Higher density
Higher melting points
Lower reactivity
Greater strength and hardness
Why are transition metals useful in construction?
The high density makes transition metals useful in construction
Why are transition metals good for cooking equipment ?
High melting points make transition metals useful for cooking equipment.
What are the special properties of transition metals ?
Can form ions with different positive charges - Iron: Fe2+ and Fe3+.Copper: Cu+, Cu2+.
Can form different colour compounds - Copper(I) sulfate is white; copper(II) sulfate is blue.
Often used as catalysts
What colour is copper (I) sulfate ?
white
What colour is copper(II) sulfate ?
blue
What is the catalyst used in the Haber process, which results in the production of ammonia ?
Iron (Fe)
What are used in catalytic converters in cars ?
Platinum (Pt) and rhodium (Rh)
What proves that transition metals are generally much less reactive than alkali metals ?
Iron takes weeks to rust when it comes into contact with oxygen and water. Sodium, however, rusts in a few seconds.
What is corrosion ?
describes the gradual destruction of metals because of chemical reactions between metals and the oxygen and water around them
What is the word equation for the rusting of iron ?
Iron + oxygen + water → hydrated iron(III) oxide.
What is the experiment for rusting ?
Take a boiling tube and put an iron nail inside under three different sets of conditions and see if it rusts:
Only water - no rust.
Only air - no rust.
Air and water - rust.
What are metals reacting with in the environment when they corrode?
Oxygen and water
What are the 3 methods to prevent corrosion?
Coatings
Sacrificial method
Galvanisation
How does coating work ?
applying a coating that acts as a barrier, such as greasing, painting or electroplating
What’s an example of coating to prevent corrosion ?
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.
What’s a disadvantage of the coating method to prevent corrosion?
A disadvantage is that any damage to the coating will lead to the metal becoming exposed and so corrosion will take place.