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Chemistry Revision Unit 2:
Structure & bonding




Nucleus ­ made up of positive protons and no charge neutrons. Is surrounded by negative
electrons ­ same number of protons and electrons P=E
Same number of protons as atomic number
Electrons are arranged in energy shells ­ either represented as dot &…

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4 covalent bonds per atom
Very rigid ­ hard, strong
Graphite:
3 covalent bonds per atom
Layers that are free to slide over each other ­ slippery, soft
Weak intermolecular forces between layers
Conducts heat & electricity because of free electrons
Silicon Dioxide:
(Silica) ­ what sand is made of…

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Metal alloy ­ ½ nickel, ½ titanium
Bend & twist it ­ if you heat it, it will return to a remembered shape
Used for glasses frames, dental braces

Nanoparticles ­
Include fullerenes: molecules of carbon, arranged in hexagonal rings, hollow balls
Can be used for: stronger & lighter building…

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1. Place food sample in a cup with a few drops of solvent to extract the colour
2. Put sports of coloured solution on a pencil baseline on filter paper
3. Roll up the sheet and put it in a beaker with some solvent
4. The solvent seeps up the…

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Reusable Not used up in Catalysts can They stop working
reactions so you can become poisoned so you have to keep
use them over and by impurities your reaction very
over ­ reduces clean.
costs

Rate of reaction = Amount of reactant used or amount of product formed/ time741

How…

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H+ + OH- H2O

Titration: acid + soluble base
Filtration: acid + insoluble base
Metal & filter: acid + metal
Precipitation: soluble salt + soluble salt insoluble salt


Soluble Insoluble
Na, K & NH4OH (ammonium) salts
Na, K & NH4OH carbonates Most carbonates
Na, K & NH4OH hydroxides Most hydroxides…

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At the Cathode, if metals ions and H+ ions are present, the metal ions will stay in the solution
if it's more reactive than the Hydrogen.
THE MORE REACTIVE IONS WILL STAY IN THE SOLUTION ­ the more reactive an element, the
keener it is to stay as ions.



At…

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Magnesium chloride Hydrogen Chlorine
Silver nitrate Silver Oxygen
Sulphuric acid Hydrogen Oxygen
Hydrochloric acid Hydrogen Oxygen

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