Paper 1 chemistry

• Atom


  The smallest part of an element that can exist
• There are about a hundred of these elements 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
  • Crystallization
  • Distillation
  • Simple distillation
  • Fractional distillation
  • Chromatography
• Filtration


  • Separates insoluble solids from liquids
• Crystallization


  • Separates soluble substances by evaporating the solvent
• Distillation


  • Separates liquids based on their different boiling points
• 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
• Subatomic particles


  • Protons have a relative mass of 1 and a relative charge of +1
  • Neutrons have a relative mass of 1 and a relative charge of 0
  • Electrons have a very small relative mass and a relative charge of -1
• Atoms are 0.1 nanometers across, with the nucleus being 1/10,000 of the atom's radius
• 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

  1. Find the percentage of each isotope

  2. Multiply the mass of each isotope by its percentage

  3. Add the two results together
• Dalton's atomic model


  Atoms are solid spheres that can't be broken down further
• Thomson's atomic model


  Electrons embedded in a large ball of positive charge, like a plum pudding
• Rutherford's atomic model


  Most of the atom is empty space, with a small positively charged nucleus
• Bohr's atomic model


  Electrons orbit the nucleus at fixed distances in shells
• Periodic table


  • Arranged by atomic number (protons) and relative atomic mass
  • Groups are columns with similar chemical properties
  • Periods are rows with the same number of electron shells
• Metals and non-metals


  • Metals are on the left and bottom, non-metals on the right and top
  • Metals form positive ions, are malleable and conductive with high melting points
• Periodic table development


  • Initially arranged by atomic weight, then by atomic number and chemical properties
  • Mendeleev left gaps for undiscovered elements and made accurate predictions about their properties
• Specific groups in the periodic table

  • Group 1 - Alkali metals
  • Group 2 - Alkaline earth metals
  • Group 7 - Halogens
  • Transition metals
• Alkali metals


  • Soft, highly reactive metals with 1 electron in their outer shell
  • 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
• Noble gases


  • Inert, unreactive elements with full outer shells

  Useful for preventing chemical reactions, e.g. in light bulbs
• Transition metals


  Block of metals between group 2 and 3 on the periodic table

  Harder, denser, higher melting points, less reactive than group 1 metals

  Form ions with different charges, form coloured compounds, useful as catalysts
• Metallic bonding


  Giant metallic lattice of positive ions surrounded by delocalized electrons

  Explains properties like conductivity, malleability, high melting points
• Ionic bonding


  Formed by transfer of electrons from metals to non-metals

  Resulting ions form a giant ionic lattice held by strong electrostatic forces
• Covalent bonding


  Sharing of electron pairs between non-metal atoms

  Can form small molecules or giant covalent structures
• Small covalent molecules


  • Hydrogen
  • Chlorine
  • Hydrogen chloride
  • Methane
  • Ammonia
  • Water
  • Oxygen
  • Nitrogen
• Small covalent molecules


  • Gases or liquids with low melting/boiling points

  Intermolecular forces, not covalent bonds, determine physical properties
• Giant covalent structures


  • Solids with high melting points

  Thousands of atoms joined by strong covalent bonds

  Examples: diamond, graphite, graphene, silica, fullerenes