Atomic structure and the periodic table

• Group

  Columns in the periodic table

  The group number tells us how many electrons are in the outer shell of the atom
• Period

  Rows in the periodic table

  Tells us how many shells the atom has
• Crytsallisation


  Seperate soluble solid from solution

  1. Pour solution into an evaporating dish and gently heat
  2. Once some of the solvent has evaporated or when crytsals start to form, remove dish from heat and leave to cool
  3. The salt should start to form crystals
  4. Filter the crystals out of the solution and leave in a warm place to dry
• Filtration


  Used to seperate an insoluble solid from liquids

  Pour mixture into filter paper, liquid will flow through into flask and insoluble will be caught in filter paper
• Chromatography


  Used to seperate a mixture of substances dissolved in a solvent

  Place a piece of paper with a spot of ink on a pencil line into some solvent.

  The solvent will start to rise up the paper, this then seperating the ink into different dyes up the paper
• Evaporation

  Used to seperate soluble solids from solutions

  1. Pour the solution into an evaporating dish
  2. Slowly heat the solution, solvent will evaporate and solution will get more concentrated
  3. Eventually crystals will start to form
  4. Keep heating crystals until dry crystals are left
• Fractional Distillation

  Used to seperate a mixture of liquids

  1. Put mixture into flask and stick a fractioning column on top. Then you heat it.
  2. Different liquids=different boiling points
  3. Liquid with the lowest boiling point evaporates first. When temperature on the thermometer matches the boiling point of this liquid, it will reach the top of the column
  4. Liquids with higher boiling points might also start to evaporate- column is cooler towards the top so will evaporate again
  5. When the first liquid has been collected, you raise the temperature until the next one reaches the top
• Simple distillation


  Used to seperate out a liquid from a solution

  1. Solution is heated, part of the solution with the lowest boiling point will evaporate first
  2. Vapour is then cooled, condenses and is the collected
  3. Rest of the solution is then left behind in the flask

  Can only be used to seperate things with very different boiling points
• Ion


  An atom that has lost or gained 1 or more electrons
• Mass number


  Number or protons and neutrons added together
• Element


  A substance made up of only one kind of atom

  They all have the same number of protons
• Isotope


  Elements that have the same number of protons but different number of neutrons
• Atomic number


  Number of protons and electrons inside the atom
• Non-Metals

  They are found on the right side of the periodic table and don't generally form positive ions. They are dull-looking, brittle and aren't always solid at room temperature. They don't generally conduct electricity and have a low density
• Metals

  They are found on the left side of the periodic table and form positive ions when they react. They form metallic bonds with eachother and strong but malleable. They are good at conducting heat and electricity and have high melting and boiling points.
• Transition metals

  They are found in the centre of the periodic table and are good conductors of heat and electricity. They are dense, strong and shiny and can have more than one ion. They are often coloured and make good catalysts
• Atom

  The smallest part of an element that can exist
• Compound


  Substances formed from two or more elements where atoms from each are held together by chemical bonds
• Ionic bonding

  Bonding between a metal and non- metal

  They form strong bonds
• Halogens

  They are group 7 non-metals with coloured vapours

  • fluorine-very reactive, yellow gas
  • chlorine-fairly reactive, poisonous dense green gas
  • bromine- dense, poisonous, red-brown volotile liquid
  • iodine- dark grey crystalline solid of purple vapour
• Group 7


  Halogens

  As you go down group 7:

  they become less reactive, have higher melting and boiling points, higher relative atomic masses, more reactive halogens will displace less reactive halogens. They can form molecular compounds and form ionic bonds with metals
• Group 1 elements


  Alkali metals

  Lithium, sodium, potassium, rubidium, caesium and francium

  They are reactive soft metals, with one electron in their outer shell which makes them very reactive. They have similar properties and have a low density.

  As you go down the group the reactivity increases, melting and boiling points decrease and there are higher relative atomic masses. They from ionic compounds with non-metals
• Group 0 elements


  Noble gases

  They all have 8 electrons in their outer shell apart from helium

  They don't need to gain or lose electrons and don't react much. They are monatomic gases meaning they are single atoms not bonded together and are colourless gases at room temperature. They are non flammable and their boiling points increase as you go down
• Who founded neutrons


  James Chadwick in 1932
• Plum pudding model


  A ball of positive charge with negative electrons embedded in it

  Discovered by JJ Thomas in 1904
• What is a catalyst?


  A catalyst is a chemical substance that increase the rate of a chemical reaction without being used up in the process
• What happens when an alkali reacts with water?

  Hydrogen and metal hydroxide are formed
• Lithium reacts with oxygen to form…

  Lithium oxide $Li_2O$
• Sodium reacts with oxygen to form…

  Sodium oxide $Na_2O$ or sodium peroxide $Na_2O_2$
• Potassium reacts with oxygen to form…


  Potassium peroxide $K_2O_2$ Or potassium superoxide $KO_2$