NAT 5- Chemistry

• Acid


  Substance with a higher concentration of hydrogen ions than hydroxide ions.
• Base


  Substance that can neutralise an acid. They come in three forms: metal hydroxide, metal oxide, and metal carbonate.
• Alkali


  Substance with a greater concentration of hydroxide ions than hydrogen ions.
• Neutral


  Substance with an equal concentration of hydrogen and hydroxide ions.
• Salt


  Product of a neutralisation reaction.
• Neutralisation


  Chemical reaction between an acid and base. Products always include water and a salt.

  
• Precipitation


  A reaction where a solid is formed.

  
• Concordant


  Titration results within 0.2 cm3 of one another.
• Spectator ion


  An ion that does not undergo chemical change, but is present for the duration of a chemical reaction.

  
• Metal oxide


  Dissolves in water to form an alkali solution
• Non-metal oxide


  Dissolved in water to form an acid solution
• Indicator


  Substance used to show the end point in a titration
• Soluble


  Term used to describe a substance if it dissolves in water.

  
• Insoluble


  Term used to describe a substance if it is incapable of dissolving in water.

  
• Pipette


  Piece of equipment used to accurately measure a known volume.

  
• Catalyst


  A substance that increases reaction rate without being used up.

  
• Proton


  Sub-atomic particle with a charge of 1+ and a mass of 1 amu. Found in the nucleus.

  
• Electron


  Sub-atomic particle with a charge of 1- and a mass of nearly nothing. Orbits the nucleus and groups itself into energy levels.

  
• Neutron


  Sub-atomic particle with no charge and a mass of 1 amu. Found in the nucleus.

  
• Electron arrangement


  The way in which electrons group themselves into shells, or energy levels.

  
• Ion


  An atom that has lost or gained electrons and so now carries a charge.
• Atomic number


  Equal to the number of protons that an atom has.

  
• Mass number


  Number of protons plus neutrons in an atom.

  
• Isotopes

  Two atoms of the same element with different mass numbers.

  
• Ionic bond


  The strong electrostatic attraction between a non-metal and a metal ion for each other. (Lost electrons of the metal are picked up by the non-metal.)

  
• Covalent bond


  Between two non-metal atoms. A shared pair of electrons.

  
• Ionic crystal lattice


  Structure formed by ionic bonding.

  
• ions are free to move


  Why do ionic substances conduct when molten or dissolved?
• Covalent molecular


  One form of covalent compound. It has low melting and boiling points due to the fact that the molecules are held together by only weak forces of attraction, not bonds, that break easily. No covalent compound, excluding graphite, conducts electricity.

  
• Covalent network


  One form of covalent compound. It has high melting and boiling points due to the strong bonds between molecules and does not generally conduct electricity.

  
• Relative atomic mass


  The average mass of an element, taking into account the relative abundance of its isotopes.
• Exothermic


  A reaction that gives off energy into its surroundings is _____. E.g, combustion.

  
• Endothermic


  A reaction that takes in energy from its surroundings is ______. E.g, a cool pack.

  
• Electrolysis


  The breaking down of an ionic compound using electricity.

  
• Linear


  A shape of molecule as seen:

  
• Angular


  A shape of molecule as seen:

  
• Trigonal pyramidal


  A shape of molecule as seen:

  
• Tetrahedral


  A shape of molecule as seen:

  
• Fuel


  Name given to a substance that can be burned to release energy

  
• Hydrocarbon


  Compound containing the elements carbon and hydrogen only.