Potassium manganate crystals dissolve in water- purple solution is formed
When diluted, colour fades but doesn't dissapear until many dilutions
Large number of particles of Potassium Manganate in very small amount of solid. Particles of K Manganate must be very small
Diffusion
Particles spreading to fill space
Example
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Bromine from one flask to another. After 5 minutes, bromine gas has diffused between both flasks. Air and bromine particles are moving randomly and there are large gaps between particles- they can easily mix together
Takes place in liquids also, but slower
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Because liquids are closely packed together and move more slowly than in a gas.
Atoms and molecules
Atoms are made up of sub-atomic particles
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Protons: Charge +1, Mass 1
Electons: -1, Mass 1/1836
Neutron: 0, 1
The only atom with no neutrons is the simplest isotype of H
Molecules are made up of 2+ atoms covalently bonded together
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Noble gas' (He, Neon, Radon etc.) exist as atoms at room temperature and pressure so the atom and molecule are the same. Molecule like noble gas' are called monoatomic molecules.
Elements, compounds and mixtures
Elements
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Elements have different, individual, chemical properties.
Iron Filings
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Element,
Grey Powder
Attracted to magnet
Reacts with HCl to form H gas
Sulphur
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Element,
Yellow Powder
Not magnetic
Does not react with HCl
Mixture
Iron and sulphate
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Mixture
Mix of grey and yellow powder
Iron attracts, Sulphur doesn't
Grey powder forms H gas with HCl. Yellow powder doesn't react
Compounds
Iron Sulphide
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Compound
Dark grey solid
Not attracted to magnet
Reacts with HCl to form Hydrogen Sulfide ( H2S)