Solids, Liquids, Gases
Solids - eg. metal, chocolate, wood. Regularly arranged particles, compacted, fixed volume, fixed shape, vibrating movement.
Liquids - eg. water, acid. Random movement, close together, connected but still fluid, quite fast moving particles, no fixed volume, adapt to container
Gases - eg. oxygen. Far apart, arranged randomly, fast moving, no fixed volume, fill a container.
Solid <--> gas - subliming, deposition
Gas <--> liquid - condensation, evaporating
Liquid<--> solid - freezing, melting
The spreading out of particles in a gas/liquid from area of higher concentration to area of lower concentration.
In gas, lighter particles move faster. Gas evens out concentration.
In liquid - in cold water diffusion is slow, in hot water diffusion is fast
Atoms, elements, compounds & mixutres
Atom - smallest particle that makes up an element
Element - substance made up of only one type of atom (found on periodic table)
Compound - when two substances are chemically bonded together. Made up of two or more types of atom.
Mixture - when two or more substances are mixed together, but not chemically bonded.
Methods of separation
Filtration - insoluble solids & soluble solids
Centrifuge - small amounts of solid held into suspension
Evaporation - soluble solids & liquids
Crystallisation - soluble substance contaminated with small impurities
Distillation - separate liquids from contaminants
Fractional distillation - separate 2 or more liquids with different boiling points
Chromatography - seperate soluble compounds from mixtures
Centrifuge - tube is placed in centrifuge and spun at high speed, solid particles are forced to the bottom of the tube by resulting outward force. Liquid is decanted off.
Crystallisation - eg. CuSO4 (copper sulphate). If you cool solution slowly, you get big crystals. If you cool quickly, you get small crystals.
Distillation - heat liquid so it evaporates and forms vapour. This goes into the condenser. The condenser should slope down into a beaker and as the vapour cools it will run down the condenser.
Fractional distillation - It is used to separate liquids. You can also do this by taking advantage of their boiling points.
Chromatography - eg. coloured ink. Rf value - Retention factor: is constant for a given compound in a given solvent/element.
Rf= y (distance travelled by spot)/x (distance travelled by solvent) always less than 1