3.3 Metals
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what are two things a structure of a metal has
A lattice of positive metal ions A sea of delocalised electrons
what is the definition of Metallic bonding
Metallic bonding is the electrostatic attraction between the positive metal ions and negative delocalised electrons
describe features of metals
Malleable- Layers of metal ions which can slide over each other conduct electricity high melting point
Why are metals malleable
They have layers of metal ions which can slide over each other when a force is applied
what bonding does a metal have
Metallic
is metallic bonding strong or weak
very strong
what are Alloys
A mixture of a metal with one or more other elements, usually other metals or carbon
Why are alloys harder than pure metals
Because they have different- sized atoms/ ions which prevent the layers from sliding over each other - this means they are less malleable
what observations could be made in a Metal + water reaction
Effervescence solid disappears
What observations can be made in a Displacement reaction
• vary • Solid changes colour • Solution changes colour
What are two observations to be made in an Acid + Metal reaction
Metal disappears Fizzing
What is the test for Hydrogen
Lit splint- Squeaky pop
As you go down the periodic table what happens
The reactivity level increase as the number of occupied electron shells increase, the attraction between the electrons and the positive nuclei is weaker making it easer to gain or loose electrons
What is reduction in terms of oxygen
loss of oxygen
What is reduction agent in terms of oxygen
takes away oxygen from something else
what is oxidation in terms of oxygen
The gain of oxygen
What is oxidising agent in terms of oxygen
gives oxygen to something else
what is the definition of Rusting
The chemical process by which iron is oxidised to form rust
what is the chemical name for rust
Hydrated iron (III) oxide
What two substances are required for rusting
Oxygen water (moisture)
How can rusting be prevented
Using barriers Sacrificial protection Galvanising
what is the barrier method for preventing rust
Coating iron in paint, oil grease or plastic prevents the iron from coming into contact with oxygen or water only works as long as the coating is in direct contact with the iron
What is the sacrificial method for preventing rust
Attach a block of more reactive metal (e.g. magnesium) to the iron this works by displacing the iron from rust as soon as the rust forms
What is the Galvanising method of preventing rust
This method specifically involves coating the iron in zinc Prevents exposure to oxygen or water zinc is more reactive than iron so even when it cracks it acts as sacrificial protection as well