Atomic Structure and the Periodic Table Flashcards
Paper 1 - C1
What is an element?
All of the atoms are the same
What is a compound?
Compounds contain two or more different elements
What is a mixture?
A mixture contains two or more substances not chemically combined together
What is a molecule?
A molecule has any elements chemically combined even if its the same element e.g. ( H20, NH3, O2, Cl2, CH4)
What is filtration used to separate?
Filtration is used to separate an insoluble solid from a liquid
What does insoluble mean?
Insoluble means that the solid will not dissolve in the liquid
How does filtration work?
-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.
What is crystallisation used to separate?
Crystallisation is used to separate a soluble solid from a liquid.
What does soluble mean?
Soluble means that the solid will dissolve in a liquid
How does crystallisation work?
-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.
How can we make crystallisation faster?
-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.
What is simple distillation used to separate?
Simple distillation is used to separate a dissolved solid from a liquid but as a result we want to keep the liquid.
What are the two stages of simple distillation?
-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.
What do we do before we carry out simple distillation?
-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.
What happens in simple distillation? And how do we carry it out?
-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.
What is simple distillation used for?
-It can be used to make sea water into drinking water.
-However, a great deal of energy is required for simple distillation.
What is fractional distillation used to separate?
Fractional distillation is used to separate a mixture of different liquids but the liquids must have different boiling points.
How do we set up fractional distillation?
-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.
How does fractional distillation work?
-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.
What happens if two liquids have very similar boiling points during fractional distillation?
-It’s much harder to separate them.
-We might also need to carry out several rounds of fractional distillation.
What is a solvent?
A solvent is a liquid that will dissolve substances.
What is paper chromatography used to separate?
Paper chromatography allows us to separate substances based on their different solubilities.
How do we carry out paper chromatography?
-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.
Why is the paper called the stationary phase?
Because the paper does not move.
Why is the solvent called the mobile phase?
Because the solvent moves.
Why does paper chromatography work?
Because different substances have different solubilites.
Why does a more soluble substance move further than a substance of less solublitiy?
This is because a more soluble substance is more attracted to the mobile phase (the solvent) than a less soluble substance.
Why do we draw our starting line in pencil?
This is because, the pen ink could dissolve in the solvent and move up the paper.
What is an electron?
A tiny negative particle.
What is the description of the Plum Pudding Model?
An atom is a ball of positive charge with negative electrons embedded in it.
