3.5 METALS Flashcards
Describe metallic structure
- Lattice of positive metal ions
- Sea of delocalised electrons
- Metal ions have their usual charges and electrons are labelled e-
Define metallic bonding
The strong electrostatic force of attraction between a lattice of positive metal ions, and a seas of delocalised electrons
Explain why metals have high melting points
- The metallic bonds are very strong
- There are lots of metallic bonds in the structure
- A lot of energy is required to break the strong metallic bonds
Explains why metals conduct electricity
The sea of delocalised electrons are free to move through the positive metal ion lattice, allowing current to flow
Explain why metals are malleable
The layers of metal ions are able to slide over each other
Define a thermal decomposition
A reaction where heat (thermal) energy is used to break down a substance
Metal carbonate thermal decomposition reaction
Metal Carbonate → Metal Oxide + Carbon Dioxide
Colour of copper carbonate
Green
Colour of copper oxide
Black
What is downward delivery
As CO2 is denser than air, carbon dioxide sinks to the bottom of a tube and stays there until it is needed
Reactivity series
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
- Aluminium
- Carbon
- Zinc
- Iron
- Lead
- Hydrogen
- Copper
- Silver
- Gold
First 6 metals of reactivity series
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
- Aluminium
Middle of reactivity series
- Carbon
- Zinc
- Iron
- Lead
Bottom or reactivity series reactivity series
- Hydrogen
- Copper
- Silver
- Gold
Metal and water reaction
Metal + Water → Metal hydroxide + Hydrogen
Observations to a metal and water reaction
- Effervescence - due to hydrogen gas being produced
- Solid disappears - Used up in the reaction
Observations to Alkali Metals reacting with water
- Solid floats - Less dense than water
- Effervescence - Hydrogen gas is produced
- Solid Moves - The effervescence propels it around the surface of the water
- Solid disappears - It is used up in the reaction
Unique reaction to potassium reacting with water
The potassium melts and produces a lilac flame
Unique reaction to sodium reacting with water
Sodium melts
Why do the alkali metals get more reactive down the group
- Reacts by losing its outer shell electron to gain a full shell
- The atoms get bigger and have more shells down the group
- The outer-electron is further from the attraction of the nucleus
- The attraction between the nucleus and outer-electron is weaker
- So less energy is needed to break the attraction
Metal and steam reaction
Metal + Steam → Metal Oxide + Hydrogen
How is a metal and steam reaction usually conducted
- In a horizontal tube
- Wet wool is heated to generate steam for the metal further down the tube to react with
- The hydrogen produced is ignited to safely destroy it
Why do metals react different with hot steam and cold water
Steam has more energy, so both bonds in the water molecule can break
Magnesium observation
Grey solid
Copper sulphate observation
Blue solution
Copper observation
Pink-orange solid
Magnesium sulphate observation
Colourless solution
Observations for displacement reaction
Solid colour change and solution colour change
Magnesium and copper sulfate reaction observations
- Solid turns from grey to pink
- Solution turns from blue to colourless
Define an ore
A substance found in the Earth’s crust as compounds bonded with oxygen and sulfur impurities
Define the term ‘native’
Substances that are found in their pure form as they are too chemically unreactive to react with oxygen and sulfur impurities
What are the only 2 native metals
Gold and SIlver
How do you separate metals more reactive than carbon
By electrolysis - Using electricity to break down their ore compounds
How do you separate ores less reactive than carbon
Carbon Displacement - The compound is heated and the carbon displaces the metal from it’s compound
What is oxidation and reduction in terms of oxygen
Oxidised - Gains oxygen
Reduced - Loses oxygen
Chemical name for rust
Hydrated iron(III) oxide
Properties of rust
Brown, dull, brittle
Iron observation
Grey, shiny, malleable solid
Stages of rusting
Iron become oxidized and then hydrated
What 2 conditions are needed for rusting to occur
Oxygen and water
How can rusting be prevented
- Coating the iron in paint, oil, grease or plastic prevents it coming into contact with oxygen or water (use of barriers)
- Sacrificial protection - by attaching a block of more reactive metal (usually magnesium) to the iron (displaces the iron from the rust as soon as it forms)
- Galvanising - Coating the iron in zinc that coats the iron preventing it coming into contact with water and oxygen, as well as acting as sacrificial protection
Disadvantage to sacrificial protection
The block of metal (usually magnesium has to be replaced often)
Disadvantage to barriers
As soon as it breaks, rusting occurs
Define an alloy
A mixture of a metal with one or more other elements, usually other metals or carbon
Why are alloys harder than pure metals
- The different-sized atoms-ions prevent the layers of metal ions from sliding over each other
- Meaning the alloy is less malleable
Use of iron
Making steel as it is more useful
Use of low-carbon steel
Ships, cars and bridges - very malleable
Use of high-carbon steel
Tools like knives and screwdrivers - less malleable than low-carbon so stiffer
Use of stainless steel
Cutlery, cooking utensils, kitchen sinks - Cr forms oxide layer that resists corrosion and so stays shiny and clean
Use of copper
Wires, cooking pans and water pipes - Excellect conductor of electricity and heat, unreactive and malleable
Uses of aluminium
Aircraft bodies, power cables - low-density, high strength and conducts
Composition of low-carbon, high-carbon and stainless steel
- 0.1% C
- 1% C
- 1%C + 10% Cr
