Atomic structure and periodic table

• how to do paper chromatography (explain)?

  1. draw a line near bottom of a sheet of filter paper - baseline

  2. make sure you use a pencil to do this as pencil marks are insoluble and don't dissolve in solvent

  3. add spot of ink to the line and place the sheet in beaker of solvent e.g water

  4. The solvent used depends on what's being tested some compounds dissolve well in water but sometimes some other solvents like ethanol are needed

  5. make sure level of solvent is below baseline as you don't want inks to dissolve into solvent

  6. place a lid on top of the container to stop the solvent evaporating

  7. the solvent will seep up the paper carrying the ink with it

  8. each different dye in the inks will move up the paper at a different rate and form a spot in a different place. If any of the dyes are insoluble they won't dissolve and would stay on baseline .

  9. when the solvent has nearly reached the top of the paper take the paper out of the beaker and leave it to dry

  10. end result is pattern of spots called a chromatogram
• Describe the process of filtration?

  1) Filter paper is folded and put into a funnel

  2) Filter allows liquid to flow through but not the solids

  3) Results with the solid in the filter paper and the liquid in another container

  Filtration can be used for purification
• Describe the process of evaporation ?

  1)Pour the solution into an evaporating dish

  2)Slowly heat the solution. The solvent will evaporate and the solution will get more concentrated. Eventually, crystals will start to form

  3)Keep heating the evaporating dish until all you have left are dry crystals
• Describe the process of crystallisation?

  Pour the solution into an evaporating dish

  Slowly heat the solution. Some of the solvent will evaporate and the solution will become more concentrated. Once some of the solvent has evaporated remove the dish from heat and leave the solution to cool.

  The salt should start to form crystals as it becomes insoluble in the cold highly concentrated solution

  Filter crystals out of solution and leave them in a warm place to dry. You could use a drying oven or a dessicator
• How can filtration and crystallisation be used to separate rock salt?

  1.Grinding-grind the mixture to make sure the salt crystals are small,so will dissolve easily.

  2.Dissolving-put the mixture in water and stir the salt will dissolve but the sand won't

  3.Filtering-filter the mixture the grains of sand won't fit through the tiny holes in the filter paper so they collect in the paper instead the salt passes through the filter paper so it's part of the solution

  4.Evaporation-evaporate the water from the salt so that it forms dry crystals
• Describe how the process of distillation is used to separate out solutions?

  The solution is heated the part of the solution that has the lowest boiling point evaporates first

  The vapour is cooled, condenses and is collected

  The rest of the solution is left behind in the flask

  The problem with simple distillation is that you can only used it to separate out things with very different boiling points, if the temp goes higher than the boiling point of that that sub they will mix again
• How can fractional distillation be used to separate a mixture of liquids?

  You pour mixture into a flask and stick a fractionating column on top then heat

  The different liquids will have different boiling points so they will evaporate any diff temps

  Lowest boiling point evaporates first when the temp matches the boiling point of this liquid it will reach the top of the column

  Liquids with higher boiling points may also start to evaporate but the column is cooler towards the top so they will only get part of the way before condensing and flowing back down towards the flask.

  When the first liquid has been collected you raise the temperature until the next one reaches the top
• Describe alpha scattering experiment?

  Alpha particles were fired at a thin sheet of gold foil, and it was expected that they would all go though the foil or only be partially deflected, instead some were deflected more than expected, and some bounced completely back. This showed that there was a concentrated positive charge in the center of atoms.
• How do alkaline metals react with water?

  They react vigorously to produce hydrogen gas and metal hydroxides-salts that dissolve in water to produce alkaline solutions

  The more reactive an alkali metal is , the more violent the reaction

  The amount of energy given out increases down the group.
• How do alkaline metals react with chlorine?

  React vigorously when heated in chlorine gas to form white metal chloride salts.

  Going down the reactions with chlorine become more vigorous
• How do alkali metals react with oxygen?

  Form metal oxides these differ in name depending on the metal
• How do group one metals differ to transition metals?

  Group 1 metals are much more reactive than transition metals they react more vigorously with water oxygen or group 7 metals

  They are also much less dense, strong and hard than transition metals and have much lower melting points
• What are halogens?

  Non-metals in Group 7 with coloured vapours fluorine is a very reactive poisonous yellow gas. Chlorine is a fairly reactive, poisonous red-by volatile liquid. Iodine is a dark grey crystalline solid or purple vapour

  They all exist as molecules which are pairs of atoms.
• What are the trends going down group 1 metals?


  Increase reactivity in

  -the outer electron is more easily lost as the attraction between the nucleus and electron decreases

  Lower melting and boiling points

  Higher relative atomic mass
• Describe the trends of group 7 elements the halogens?

  As you go down becomes less reactive

  - it's harder to gain extra electron because further shell

  Higher melting and boiling points

  Higher relative atomic masses
• Facts about group 0 elements

  Also known as noble gases they are all inert(do not react because of full outer shell), colourless at room temperature

  Un reactive have full outer shell of 8 electrons except helium with 2

  They exist as monatomic gases-singles atoms not bonded to each other

  Non flammable
• What are trends of noble gases?

  Boiling points inc as you go down along with relative atomic masses this is bc of increase of number of electrons in each atom leading to greater intermolecular forces