C1: atomic structure

• Atom


  Consists of a nucleus with protons and neutrons, and electrons orbiting the nucleus
• Proton


  • Positive charge of +1, mass of 1 atomic mass unit, located in the nucleus
• Neutron


  • Neutral charge, mass of 1 atomic mass unit, located in the nucleus
• Electron


  • Negative charge of -1, mass of 1/2000 atomic mass unit, orbits the nucleus in shells
• The atomic number indicates the number of protons in an atom
• The relative atomic mass is the number of protons plus the number of neutrons
• Development of the atomic model

  1. Dalton - atoms as simple spheres

  2. Thomson - atoms contain electrons in a positive sphere

  3. Rutherford - atoms have a positive nucleus and mostly empty space

  4. Bohr - electrons in specific orbitals

  5. Chadwick - discovery of the neutron
• Element


  Consists of only one type of atom
• Compound


  Consists of two or more different types of atoms chemically bonded together
• Mixture


  Consists of two or more elements or compounds not chemically bonded
• Separation techniques for mixtures

  1. Distillation - evaporation, condensation, collection

  2. Crystallization - evaporation of solvent to leave solid

  3. Chromatography - separation based on solubility
• Distillation apparatus


  1. Water goes in at the bottom

  2. Water comes out at the top

  3. Water stays cold throughout the whole time in the condenser
• Crystallization


  Technique to separate soluble solids
• Soluble solids


  Solids that have been dissolved in a liquid, e.g. salt in water
• Crystallization


  1. Evaporate off the liquid

  2. Leaves the solid
• Chromatography


  Separates using solubility
• Mixtures


  • Mixture B
  • Mixture C
• Mixtures have at least two components
• Mixture A and C have two of the same component
• Mixture C and B have two of the same component
• Chromatography


  • The chromatography paper has a liquid (usually water) that rises up and takes the different components in the mixture with it
  • More soluble components travel further up the paper
  • Less soluble components stay at the bottom as they are more attracted to the stationary phase (paper)
• Niels Bohr came up with a rule for drawing electron configurations (2-8-8 rule)
• Atoms


  • Sodium
  • Chlorine
  • Boron
• Drawing electron configurations


  1. Write the element name

  2. Draw 2 electrons in the first shell

  3. Draw electrons in a north-east-south-west pattern
• Ions


  Atoms that have lost or gained electrons, becoming charged
• Positive ion


  Atom has lost electrons, has more protons than electrons
• Negative ion


  Atom has gained electrons, has more electrons than protons
• Isotopes of carbon


  • Carbon-12
  • Carbon-13
  • Carbon-14
• Isotopes


  Atoms with the same number of protons and electrons but different numbers of neutrons
• State symbols


  S = solid, G = gas, L = liquid, Aq = aqueous (dissolved in water)
• Balancing chemical equations


  1. Count atoms on each side

  2. Balance metals/non-oxygen/hydrogen first

  3. Then balance oxygen and hydrogen
• All chemical reactions must be balanced