Paper 1

• Atom


  Smallest part of an element that can exist
• Element


  One type of atom
• Compound


  2 or more elements chemically combined
• Mixture


  2 or more substances mixed together, not chemically combined
• Crystallisation


  Separates a soluble solid from a solution
• Simple distillation


  Separates 2 liquids that have different boiling points
• Fractional Distillation


  Separates a range of different liquids all with different boiling points
• Chromatography


  Separates substances with different solubilities
• John Dalton


  He thought that all matter was made of tiny particles called atoms, which he imagined as tiny spheres that could not be divided
• Plum Pudding model


  JJ Thomson suggested that the atom was a ball of positive charge with negative electrons embedded in it
• Alpha Scattering


  Results from Rutherford's alpha scattering experiments led to the plum-pudding model being replaced by the nuclear model. Positively charged alpha particles were fired at thin gold foil, most went straight through but a few were scattered in different directions. This showed the mass and positive charge of the atom was in the nucleus, and the electrons orbited the nucleus
• Nuclear model


  The centre of the atom was called the nucleus
• Bohr model


  Adapted the nuclear model by suggesting electrons orbit the nucleus at specific distances, on energy levels or shells

  
• Chadwick discovered neutrons
• Atomic Structure


  Number of protons = Number of electrons
• Isotopes


  Atoms of the same element can have different numbers of neutrons
• Calculating average atomic mass

  (isotope 1 mass x abundance) + (isotope 2 mass x abundance)) ÷ 100
• Periodic Table


  Columns = Groups, Rows = Periods
• John Newlands


  Ordered his periodic table in order of atomic mass, realised similar properties occurred every eighth element - 'law of octaves'
• Dmitri Mendeleev


  Ordered his periodic table in order of atomic mass, but not always strictly - left gaps for undiscovered elements, swapped some elements to make properties fit better
• Metals


  Elements that react to form positive ions
• Non-metals


  Elements that do not form positive ions
• Group 0 - Noble gases

  • All have full outer shells, unreactive, boiling points increase with increasing relative atomic mass
• Group 1 - Alkali Metals


  • Metals that react vigorously with water, oxygen, and chlorine, reactivity increases going down the group
• Group 7 - Halogens


  • Similar reactions due to 7 electrons in outer shell, reactivity decreases, melting point increases, can form ionic or covalent compounds

  
• Displacement Reaction


  A more reactive element pushes out a less reactive element in a reaction
• Transition Metals


  • Harder, stronger, higher melting points and densities, less reactive than Group 1, form ions with different charges, form coloured compounds, can act as catalysts
• Ionic Bond


  Bond between a metal and a non-metal, electrons are transferred

  
• Covalent Bond


  Bond between 2 non-metals, electrons are shared
• Metallic Bond


  Bond in metals, giant structure of regularly arranged ions surrounded by delocalised electrons
• Ionic Compounds


  • Giant ionic lattices held together by strong electrostatic forces, high melting/boiling points, don't conduct electricity when solid but do when molten or dissolved
• Ion charges


  Group 1 metals = 1+, Group 2 metals = 2+, Group 6 non-metals = 2-, Group 7 non-metals = 1-

  
• Covalent Molecules


  • Strong covalent bonds but weak intermolecular forces, usually gases or liquids, low melting/boiling points, don't conduct electricity
• Giant Covalent Substances


  • Strong covalent bonds throughout giant lattice structure
• Polymers


  Long chains of small molecules joined by covalent bonds, weak forces between chains
• Alloys


  • 2 metals mixed together, atoms are different sizes disrupting the regular structure, makes them harder
• Diamond


  • Each carbon atom bonded to 4 others, very hard, very high melting point, doesn't conduct electricity
• Graphite


  • Layered structure, each carbon atom bonded to 3 others, weak forces between layers, can conduct electricity due to spare electron, high melting point, slippery
• Graphene


  Single layer of graphite, can conduct electricity, incredibly thin but strong
• Fullerenes


  Molecules of carbon atoms that make hollow shapes, used to carry drugs, carbon nanotubes are thin fullerenes that strengthen materials