Paper 1 Key Words

• Bohr

  Developed the Bohr model as a modification of Rutherford’s model, proposing that electrons exist in shells of fixed energy around the nucleus
• Dalton

  Developed an early atomic model which describes atoms as solid spheres, stating that different spheres made up the different elements. He also stated that atoms were identical and they could not be divided
• Rutherford

  Designed the gold foil experiment which led to him proposing the nuclear atomic model which stated that atoms were made up of a small positively charged nucleus which was surrounded by empty space and a layer of orbiting electrons
• Thomson

  Thomson discovered that atoms contain electrons and that they are overall neutral
• Anion

  A negative ion, when an atom has gained electrons
• Cation

  A positive ion, when an atom has lost electrons
• Sublimation

  Solid -> gas
• Empirical formula

  The simplest whole number ratio of atoms of each element in a compound
• Condensation

  Gas -> liquid
• Alloys

  A metal compound made by combining two or more metals together
• Chromatography

  A process used to separate substances in a mixture using a mobile and stationary phase
• Covalent bond

  A shared pair of electrons between two non metals
• Crystallisation

  Heating the solution until crystals start to form and then leaving the solution to cool and filtering the formed crystals from the solution
• Electrostatic forces

  The strong forces of attraction between oppositely charged ions
• Evaporation

  Separating soluble solids from solutions by slowly heating it in an evaporating dish so that the solvent evaporates to leave the dry crystals
• Filtration

  Separating an insoluble solid from a solution
• Fractional distillation

  Separating a mixture of liquids that have different boiling points so they can be separated into different fractions within a fractioning column
• Fullerenes

  Molecules of carbon atoms with hollow shapes
• Gas chromatography

  A tube is packed with a solid and a gas is passed through the column under pressure at high temperature and each component takes a different time to pass through the tube
• Graphene

  A single layer of graphite with properties that make it useful in electronics and composites
• Graphite

  A giant covalent structure which is made up of carbon atoms which each form three covalent bonds with three other carbon atom, forming layers of hexagonal rings which have no covalent bonds between them. There is one delocalised electron per carbon atom which is free moving to carry charge
• Intermolecular forces

  The forces which exist between molecules
• Ionic compound

  Chemical compound formed of ions that are held together by strong electrostatic forces
• Locating agent

  A chemical which reacts with a colourless substance to produce a coloured product used in paper chromatography to help identify the substances stationary phase
• Simple distillation

  Separating a liquid from a solution by heating the solution so only the liquid with the lowest boiling point evaporates. The gas is then condensed before being collected as a liquid
• Solution

  The solute dissolved in the solvent
• Solute

  Soluble solids
• Solvent

  A liquid the solute dissolves in
• Plasticisers

  Act like oil and enable the polymer to slide over one another
• Crosslinking

  Makes the material tougher, less flexible and increases its melting point
• Activation energy

  The energy required for a reaction to occur
• Anode

  The positive electrode where negatively charged ions lose electrons in oxidation reactions
• Avogadro’s constant

  The number of atoms, molecules or ions in a mole of a given substance
• Cathode

  The negative electrode where positively charged ions gain electrons in reduction reactions
• Electrode

  A solid conductive material through which electricity can flow and are used in electrolysis to conduct electricity
• Electrolysis

  The splitting up of an ionic compound using electricity
• Electrolyte

  A solution containing free moving ions to carry charge from the molten or aqueous ionic substance
• Endothermic reaction

  A reaction where energy is taken in from the surroundings, bond breaking is endothermic
• Exothermic reactions

  A reaction where energy is transferred to the surroundings, bond making is exothermic
• Intert

  Unreactive