Atomic Structure and the Periodic Table

All of the atoms are the same

Compounds contain two or more different elements

A mixture contains two or more substances not chemically combined together

A molecule has any elements chemically combined even if its the same element e.g. ( H20, NH3, O2, Cl2, CH4)

Filtration is used to separate an insoluble solid from a liquid

Insoluble means that the solid will not dissolve in the liquid

-First we use a filter funnel and a filter paper. -Then we start by pouring your mixture into the filter paper. -The liquid(filtrate) then will pass through the tiny pores in the filter paper. -However, the solid material will be trapped as it cannot pass through the filter paper. -Now, we have our liquid separated from our solid.

Crystallisation is used to separate a soluble solid from a liquid.

Soluble means that the solid will dissolve in a liquid

-If we leave the solution in a beaker for a few days, then the water will evaporate. -This will leave behind crystals of the solution. -This will change the state symbol from (aq) to (s) as the solution is no longer dissolved in water and is now a solid.

-If we gently heat the solution to evaporate the water. -However, we need to be careful as certain chemicals will break down if we heat them. -Meaning it is sometimes better to allow the water to evaporate on its own.

Simple distillation is used to separate a dissolved solid from a liquid but as a result we want to keep the liquid.

-First, we evaporate the liquid by heating, which will turn the liquid into a vapour. -Next, we condense the vapour back to a liquid by cooling.

-First, we place our solution with the liquid and dissolved solid into the flask which is connected to a continuous glass tube and is surrounded by a jacket called the condenser. -Next, make sure cold water from the tap is continuously running through the condenser so the internal glass tube is cold then the water will run into the sink. -Make sure a thermometer is also connected to the apparatus.

-First, we start by heating our solution by using a Bunsen burner which will make the liquid start to evaporate turning into a vapour. -Now, the vapour will rise up the glass tube. -As the vapour passes over the thermometer, the thermometer reading increases -Heat the solution till it boils. -Next, the vapour passes into the condenser (which is cold because of the cold tap water) which causes the vapour to condense. -This will make it turn back to a liquid as it passes through the condenser. -Now we can collect the liquid in the beaker. -At the end, we are also left with crystals of our solid in the flask.

-It can be used to make sea water into drinking water. -However, a great deal of energy is required for simple distillation.

Fractional distillation is used to separate a mixture of different liquids but the liquids must have different boiling points.

-We get a flask with a mixture of different liquids with different boiling points. -This flask is attached to a long column containing hundreds of glass beads which is called the fractionating column. -At the top of the fractionating column, we have a thermometer. -Then we have a condenser which is connected to the fractionating column.

-We start by gently heating our mixture and our liquids will start to evaporate but the one with the lower boiling point will evaporate more easily. This will give us a mixture of different vapours. -This mixture will make their way into the fractionating column. -When they reach the fractionating column they will condense and drip back into the flask where the liquids will evaporate again. -This repeated evaporation and condensation increases the amount of the lower boiling point chemical in the fractionating column. -As the warm vapours pass up the column they reach the thermometer and the temperature on the thermometer begins to rise. -When this temperature rises, this means that the mixture of the different vapours is passing over the thermometer. -However, the mixture will contain more of the chemical with the lower boiling point. -These vapours will then pass through the condenser and will turn back into a liquid but it is still a mixture of the two chemicals. -When the temperature of the thermometer stops rising it will be the lower of the boiling points. -At this point there is only one chemical passing through the condenser, and as the chemical condenses we can collect it in a fresh beaker. -After a while the temperature on the thermometer begins to rise again which means again a mixture of vapours is passing through the condenser. -This mixture will mainly contain the chemical with the higher boiling point. -When the temperature reaches a constant temperature, we’re now collecting a relatively pure sample of the higher boiling point chemical.

-It’s much harder to separate them. -We might also need to carry out several rounds of fractional distillation.

A solvent is a liquid that will dissolve substances.

Paper chromatography allows us to separate substances based on their different solubilities.

-First we take a piece of chromatography paper. -We then draw a pencil line near the bottom of the paper. -Next we put a dot of our first colour on the pencil line. -Next to it, we put a dot our second colour. -We now place the bottom of the paper into a solvent. -The solvent will now make its way up the paper. -It dissolves the ink in the two coloured dots. -Now the ink has carried up the paper dissolved in the solvent. -Now if the colour has made one dot at the end of the chromatography we know that it was a pure colour but if it made more than one colour it was a mixture of two colours.

Because the paper does not move.