Chemistry Unit 2
- Created by: trinaevans76
- Created on: 04-05-15 10:35
Ionic bonding
Forms Giant Covalent regular Lattice
Strong electrostatic attraction
High Melting/Boiling points
Conductors of electricity when :
- Molten
- In solution
Forms with metals + non-metals
Covalent Bonding
1. Simple Molecular
Strong covalent bonds
Small molecules
Weak forces of attraction
Low Melting/boiling points
Poor conductor of electricity - no ions
2. Giant Covalent
Strong bonds
High Melting/Boiling points
Do not conduct electricity
Giant Covalent structures
1. Diamond
4 covalent bonds on each atom --> rigid structure
2. Graphite
Each atom has 3 bonds
Layers can slide --> soft
Weak intermolecular forces between layers
One delocalised electron on each atom
Good conductor of electricity and heat
Metallic Structures
Giant structure
Delocalised electrons from the outer shell of every metal atom
Good conductor of electricity/heat
Strong electrostatic attraction between positive ions and electrons
Regular structure
Layers can slide --> malleable
Nanomaterials
Nanoparticle = 1-100 nanometres across
Only a few hundred atoms
Uses :
Catalysts
Stronger, lighter building materials
Deoderant
Computer chips - conductors of electricity
Polymers
Thermosoftening Polymers :
Weak intermolecular forces
Free to slide over eachother
No cross links
Easy to melt - can remould
Thermosetting Polymers :
Strong intermolecular forces with cross links
Do not soften when heated
Strong hard and rigid
Gas Chromatography
1. Sample is injected as a gas
2. Carrier gas moves sample through solid in column
3. Substances move through at different speeds and are separated
4. The detector shows the retention time
This can be linked to a Mass Spectrometer
This is under a vacuum to stop molecules colliding
1. Sample is ionised
2. Sample put through magnetic field to separate it
3. A Spectra is produced
This tells you the relative formula mass of the compound
Mr = peak with highest mass
Chemical Analysis
Adding NaOH
Iron II - Green Precipitate
Aluminium - White Precipitate Redissolves in excess NaOH
Iron III - Brown Precipitate
Copper - Blue Precipitate
Calcium - White Precipitate
Magnesium - White Precipitate
Adding AgNO3
Chlorine - White Precipitate
Bromine - Cream colour
Iodine - Yellow colour
Chemical Analysis 2
Flame Test :
Lithium - Crimson
Sodium - Yellow
Potassium - Lilac
Calcium - Red
Barium - Green
Copper - Blue / Green
SO4 test :
Add HCl and sodium sulphate and add to water and add Barium Chloride - Acid + white precipitate
CO3 test :
Add to HCl, collcet gas and bubble it through limewater - White precipitate
Neutralisation Reactions
Acid + Metal --> Salt + Hydrogen
Acid + Metal Oxide → Salt + Water
Acid + Metal Hydroxide → Salt + Water
Acid + Alkali --> Salt + Water
Ammonia + Acid makes a fertiliser
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