paper 1 chemistry

• Atom


  The smallest part of an element that can exist
• There are about a hundred of these atoms shown in the periodic table
• Compound


  A substance formed by chemical reactions where different elements join together in fixed proportions
• Chemical symbol formula


  A way to represent a compound, e.g. H2O
• Naming ionic compounds


  1. Name of metal

  2. First syllable of non-metal

  3. Add 'ide'
• Naming compounds with oxygen

  1. Name of metal

  2. First syllable of non-metal

  3. Add 'ate'
• Mixture


  Two or more elements or compounds that are not chemically combined together
• Physical processes to separate mixtures

  • Filtration
  • Crystallisation
  • Distillation
  • Simple distillation
  • Fractional distillation
  • Chromatography
• Filtration


  • Separates insoluble solids from liquids
• Crystallisation


  • Separates soluble substances by evaporating the solvent
• Distillation


  • Separates liquids based on their different boiling points
• Simple distillation


  • Separates two different liquids
• Fractional distillation


  • Separates multiple different liquids
• Chromatography


  • Separates substances based on how well they are retained by a stationary phase while a mobile phase passes through
• In paper chromatography, the start line must be drawn in pencil and the solvent shouldn't come above that line
• Nuclear model of the atom


  Protons and neutrons in the nucleus, electrons orbiting the outside
• Atom


  • Protons = atomic number, electrons = atomic number, neutrons = mass number - atomic number
• Relative mass


  Protons and neutrons = 1, electrons = very small
• Relative charge


  Protons = +1, electrons = -1, neutrons = 0
• Atoms are 0.1 nanometers across
• Isotopes


  Atoms of the same element with the same number of protons but different numbers of neutrons
• Calculating relative atomic mass of a sample with two isotopes

  Multiply percentage of each isotope by its mass, then add the results
• Dalton's atomic model


  Solid spheres that can't be broken down further
• Thomson's atomic model


  Electrons embedded in a large ball of positive charge
• Rutherford's atomic model


  Positive nucleus with electrons orbiting, most of atom is empty space
• Bohr's atomic model


  Electrons orbiting at fixed distances from the nucleus in shells
• Chadwick's discovery of the neutron helped explain isotopes
• Periodic table


  Arranged by atomic number, groups have same outer shell electrons, periods have same number of shells
• Periodic table groups


  • Group 1 (alkali metals)
  • Group 2
  • Group 6
  • Group 7
  • Transition metals
• Metals


  • Form positive ions, malleable, conductive, high melting points
• Periodic table


  Named because properties repeat periodically
• Initial periodic tables were arranged by atomic weight, not atomic number
• Mendeleev left gaps for undiscovered elements and accurately predicted their properties
• Group 1 (alkali metals)


  Soft, highly reactive metals with 1 electron in outer shell
• Alkali metals react with oxygen to form metal oxides
• Three specific groups in the periodic table

  • Group 1 (Alkali metals)
  • Group 7 (Halogens)
  • Group 0 (Noble gases)
• Alkali metals


  Soft, highly reactive metals with one electron in their outer shell
• Alkali metal reactions


  1. Lose electron

  2. React with oxygen to form metal oxides

  3. React with water to form metal hydroxides

  4. React with chlorine to form metal chlorides
• Halogens


  Group 7 elements that all have seven electrons in their outer shell and form diatomic molecules
• Halogens vs Alkali metals

  Halogens gain electrons, become more reactive going up the group

  Alkali metals lose electrons, become more reactive going down the group