Chapter 2: Atoms - created from Mind Map

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Dilution of coloured substances

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

Takes place in liquids also, but slower

Atoms and molecules

Atoms are made up of sub-atomic particles

Molecules are made up of 2+ atoms covalently bonded together

Elements, compounds and mixtures

Elements

Mixture

Compounds

Iron Filings

Sulphur

Iron and sulphate

Iron Sulphide

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

Because liquids are closely packed together and move more slowly than in a gas.

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

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 have different, individual, chemical properties.

Element,

Grey Powder

Attracted to magnet

Reacts with HCl to form H gas

Element,

Yellow Powder

Not magnetic

Does not react with HCl

Mixture

Mix of grey and yellow powder

Iron attracts, Sulphur doesn't

Grey powder forms H gas with HCl. Yellow powder doesn't react

Compound

Dark grey solid

Not attracted to magnet

Reacts with HCl to form Hydrogen Sulfide ( H2S)

Seperation of mixture:

Filtration- seperate undissolved solid from a mixture of solid and liquid soloution (sand from sand and water)

Evaporation- seperate a dissolved solid from liquid (NaCl from NaCl and Water)

Crystallisation- seperate a dissolved solid from a solution when solid is more soluble in hot than cold (CuSO4 from CuSO4 in H20)

Fractional distallation- seperate two or more liquids (ethanol and water)

Paper Chromotography- seperate substances that have different solubilities in a given solution.

Seperation of compounds:

Sometimes heating compound works. Mercury oxide decomposes (breaks down) into mercury and oxygen when heated.

2HgO = 2Hg + O2

THERMAL DECOMPOSITION!!!

Or electricity will decompose it- if an electric current is passed through molten lead bromide, it breaks down to lead and bromide.

ELECTROLYSIS!!

Chapter 2: Atoms

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