key words chem

• Acid


  a substance that dissolves in water producing hydrogen ions (h+(aq))
• activation energy 


  the minimum energy needed for a reaction to occur
• alkali 


  a soluble base
• allotropes

  different forms of the same element, in the same state
• alloy


  a mixture of two or more elements, at least one of which is a metal, and the resulting mixture has metallic properties
• anhydrous

  a substance that does not contain water of crystallisation
• anti-bumping granules


  added to the mixture in the distillation flask to promote smooth boiling
• aqueous solution


  a solution in which the solvent is water
• atomic number


  the number of protons in an atom
• anion


  a negative ion
• base


  a metal oxide or metal hydroxide that neutralises an acid to produce a salt and water
• boiling point


  the temperature at which a liquid changes into a gas
• catalyst


  a substance that increases the rate of a reaction without being used up
• cation


  a positive ion
• compound


  two or more elements chemically combined
• concentrated acid


  contains a large number of acid particles dissolved per unit volume
• concentration (g/dm³)


  the mass of a solid in grams dissolved in 1dm³ of solution
• concentration (mol/dm³)


  the number of moles of a solid dissolved in 1dm³ of solution
• condensation


  the change of state from gas to liquid when cooled
• covalent bond

  a shared pair of electrons
• delocalised electrons


  electrons that are free to move throughout a whole structure
• desalination


  the process of removing dissolved substances from sea water
• diatomic 


  two atoms covalently bonded in a molecule
• dilute acid 


  contains a small number of acid particles dissolved per unit volume
• distillate


  the liquid that is cooled from the vapour and collected during distillation
• ductile 


  the metal can be drawn into a wire
• element 


  a substance that consists of only one type of atom
• empirical formula 


  the simplest whole number ratio of atoms of each element in a compound
• endothermic reaction 


  a reaction in which heat energy is taken in
• evaporation


  the change of state from liquid to gas when heated
• exothermic reaction


  a reaction in which heat energy is given out
• fermentation


  the breakdown of sugars to produce ethanol and carbon dioxide
• filtrate 


  the liquid which passes through the filter paper during filtration
• finite resource 


  a resource that once used, cannot be replaced in a human lifetime
• formulation


  a mixture that has been designed as a useful product. it is formed by mixing together several different substances in carefully measured quantities to ensure the product has the required properties
• fraction


  the distillate collected at each different temperature in fractional distillation
• giant ionic lattice


  a three-dimensional structure of oppositely charged ions held together by ionic bounds
• giant covalent structure 


  a three-dimensional structure of atoms that are joined by covalent bonds
• group


  a vertical column in the periodic table
• hydrated

  a substance that contains water for crystallisation