C1: Atomic structure and the periodic table

• Nucleus


  Contains protons and neutrons
• Electrons


  Orbit around the nucleus in rings
• Proton


  • Mass 1
• Electrons

  • Mass 0 (negative charge 1-)
• Atom


  Radius of 0.1nm
• Ions


  Atoms that lose or gain electrons
• Elements


  Different types of atoms
• Atomic number


  Number of protons determines what element an atom is
• Atomic mass


  Bigger number is protons + neutrons
• Atomic number


  Smaller number is proton number
• Hydrogen


  Smallest element
• Isotopes


  Different forms of the same element with the same number of protons but a different number of neutrons
• Relative atomic mass (Ar)

  Average mass of all the isotopes that make up an element
• Molecules


  Group of 2 or more atoms held together by chemical bonds
• Compounds


  Contain two or more different elements held together by chemical bonds
• Compounds are always found in the same proportions (ratio of each atom)
• Mixtures


  Two or more substances not chemically combined together, can be separated by filtration, crystallisation or distillation
• Solutions


  Have soluble solids dissolved in them
• Filtration


  Separates insoluble solids from liquids using a funnel and filter paper
• Evaporation


  Solvent evaporates and crystals form when solution is heated in an evaporating dish
• Crystallisation


  Solution is heated gently in a water bath, crystals form and are filtered and dried
• Simple distillation


  Separates a liquid from a solution e.g. pure water from sea water
• Fractional distillation


  Separates mixtures of liquids by passing vapours through a fractionating column
• Atomic theory states that everything is made from tiny particles that can't be broken down any further (Democritus)
• John Dalton described atoms as solid spheres, and different types of these atoms made up different elements
• JJ Thompson made the Plum Pudding model which means that atoms are balls of positive charge with discrete negatively charged particles scattered throughout
• Rutherford conducted the alpha scattering particle experiment and made the nuclear model with a positive compact nucleus surrounded by a cloud of negative charge
• Niels Bohr suggested that electrons orbit the nucleus in shells
• Rutherford later discovered protons and James Chadwick discovered neutrons
• Outer shell


  Most atoms have an incomplete outer shell so they are unstable and have to react with other atoms to gain or lose electrons to have a full outer shell
• Noble gases


  Have full outer shells so they are generally unreactive (inert)
• First shell


  Has the lowest energy level
• The periodic table is arranged in increasing atomic numbers
• Mendeleev's periodic table was arranged in increasing atomic mass
• Atoms in the same group

  Have similar properties because they have the same number of electrons in their outer shells
• Mendeleev's periodic table was accepted because he left space for atoms that had not yet been discovered and he predicted their properties
• Metals


  Form positive ions when they react
• Reactivity of metals


  More reactive the lower down they are because the forces of attraction are weaker and the outermost electron can be lost more easily
• Metallic bonding


  Metals are very strong
• Metals


  • Malleable
  • Good conductors of heat and electricity
  • High melting and boiling points
  • Shiny and sonorous