C1- Atomic structure and the periodic table

• What are the features of the nucleus?

  . In the middle of the atom

  . Contains protons and neutrons

  . Positive charge

  . Almost the whole mass of the atom is concentrated in the nucleus
• What are the relative masses of the subatomic particles?

  Proton: 1

  Neutron: 1

  Electron: Very small
• What are the charges of the subatomic particles?

  Proton: +1

  Neutron: 0

  Electron: -1
• What are the features of electrons?

  . Move around the nucleus in electron shells

  . Negatively charged and tiny; cover a lot of space

  . The volume of their orbits determine the size of their atom

  . Virtually no mass
• How are protons and electrons related?

  Number of protons= number of electrons

  This means that atoms are neutral, as the positive and negative charges cancel each other out
• What does the atomic number tell you?

  How many protons are in an atom
• What does the mass number tell you?

  The total number of protons and neutrons in an atom
• What determines the type of element an atom is?

  Number of protons
• What is an ion?

  An atom/ group of atoms that have lost or gained electrons
• What is an isotope?

  Different forms of the same element, which have the same number of protons but a different number of neutrons
• What is the formula to find relative atomic mass?

  Relative Atomic mass (Ar)=

  sum of (Isotope abundance x isotope mass number)/sum of all abundances in the isotope
• What is a compound?

  Substances formed from two or more elements, the atoms of each are in fixed proportions throughout the compound and they're held together by chemical bonds
• What does a chemical reaction do?

  Separates the original elements of a compound back out again.

  During a chemical reaction, at least one new substance is made. You can usually measure a change in energy, such as temperature change, as well
• What does a compound consisting of a metal and a non-metal contain?

  Ions
• What does a compound with two or more non-metals contain?

  Molecules
• How are the properties of a compound related to the properties of the original elements?

  Chemical properties are different from the properties of the original elements.
• What is a mixture?

  Two or more substances not chemically combined together

  The parts of a mixture can either be elements or compounds, and they can be separated out by physical methods
• What physical methods can a mixture be separated by?

  . Filtration

  . Crystallisation

  . Simple distillation

  . Fractional distillation

  . Chromotography
• What is air a mixture of?

  Gases, mainly nitrogen, oxygen, carbon dioxide and argon
• What is crude oil a mixture of?

  Different lengths of hydrocarbon molecules
• How are the properties of a mixture related to the properties of the original elements?

  The properties of a mixture are a combination of the properties of the original elements.
• What equipment is needed in the paper chromatography practical?

  . Beaker

  . Filter paper

  . An ink contains different dyes

  . Pencil (to draw a line)

  . Shallow solvent (inside beaker)
• What happens during the paper chromatography practical (part 1- preparation)

  1: Draw a line near the bottom of a sheet of filter paper using a pencil

  2: Add a spot of the ink to the line and place the sheet in a beaker of solvent (usually water, but ethanol may be needed)

  3: Place filter paper inside the beaker, making sure that the ink isn't touching the solvent

  4: Place a lid on top of the container to stop the solvent from evaporating
• What happens during the paper chromatography practical (part 2- experiment)

  5: The solvent seeps up the paper, carrying the ink with it

  6: Each different dye will move up the paper at a different rate so the dyes will separate out. Each dye will for a spot in a different place

  
  

  7: If any of the dyes are insoluble in the solvent then they will remain on the baseline

  
  

  8: When the solvent has nearly reached the top of the paper, take the paper out of the beaker and leave it to dry

  
  

  9: The end result is a pattern of spots called a chromatogram
• Why is a pencil used to draw a line?

  Pencil marks are insoluble and won't dissolve in the solvent
• What is filtration used? 

  Filtration is used to separate an insoluble solid from a liquid. It is useful for separating sand from a mixture of sand and water, or excess reactant from a reaction mixture.
• What equipment is used in the filtration practical?

  . Mixture of solvent and insoluble solute

  . Beaker

  . Filter paper

  . Filter funnel
• What happens during the filtration practical?

  1: A filter funnel, containing filter paper, is placed inside of the beaker

  2: The mixture of solvent and insoluble solute is pored through the filter funnel- this works because the filter paper has tiny holes or pores in it, which are large enough to let small molecules and dissolved ions 

  through, but not the much larger particles of undissolved solid.

  3: The liquid drips through the filter paper into the beaker but the solid particles are caught in the filter paper
• When else can filtration be used?

  During purification, for example solid impurities in the reaction mixture
• What equipment is used in the evaporation practical?

  . Evaporating dish

  . Bunsen burner (or a water bath/electric heater)

  . A stand for the dish, such as a tripod
• Describe the evaporation practical?

  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
• When might you have to use the crystallisation practical instead of evaporation?

  Evaporation is a quick way of separating soluble salt from a solution; it only works if the salt does not decompose when it is heated

  If the salt will decompose, then crystallisation must be used
• What equipment is needed in the crystallisation practical?

  . Solution

  . Evaporating basin

  . Bunsen Burner
• What happens during the crystallisation practical?

  1: Pour the solution into an evaporating dish and gently heat the solution. Some of the solvent will evaporate and the solution will get more concentrated

  2: Once some of the solvent has evaporated, or when crystals have started to form, remove the dish from the heat and leave the solution to cool

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

  4: Filter the crystals out of the solution, and leave them in a warm place to dry
• When is evaporation and crystallisation used?

  To produce solid crystals from a solution. For example, crystallisation is used to obtain copper sulfate crystals from copper sulfate solution.
• What is rock salt?

  . A mixture of salt and sand

  . Salt and sand are both compounds; salt dissolves in water and sand doesn't.

  . Is separated using filtration and crystallisation
• How can rock salt be separated?

  1: Grind the mixture to ensure then salt crystals are small, so will dissolve easily

  2: Put the mixture in water and stir. The salt will dissolve, but the sand won't

  3: Filter the mixture. The grains of sand won't fit through the tiny holes in the filter paper, so they collect on the paper instead. The salt passes through the filter paper as it's part of the solution

  4: Evaporate the water from the salt to that it forms dry crystals
• When is simple distillation used?

  Simple distillation is used to separate a solvent from a solution. It is useful for producing pure water from seawater.
• Why does simple distillation work?

  Because the dissolved solute has a much higher boiling point than the solvent:

  • When the solution is heated, solvent vapour leaves the solution. It moves away and is cooled and condensed.
  • The remaining solution becomes more concentrated as the amount of solvent in it decreases.
• What equipment is used in the simple distillation practical?

  A) Flask

  B) Sea water

  C) Heat

  D) Pure distilled water

  E) Water in

  F) Condenser

  G) Water out

  H) thermometer