Key concepts

• Solutions with more H+ than OH- contain free H+ ions
• nitrates are soluble
• common chlorides are soluble except for silver and lead
• common sulfates are soluble except for lead, barium and calcium
• common carbonates and hydroxides are insoluble except for sodium, potassium and ammonium
• Atoms lose or gain electrons to form ions. Ions have full outer shells.
• atomic number = number of protons.

  charge = amount of electrons compared to protons

  eg F- has 1 more electron than proton
• An ion that enters the solution from two different sources is a common ion
• avogadro's constant is the number of particles in 1 mole of particles. It has a value of 6.022 x 1023
• mass / (mole number x constant) = 1 atom

  eg. 984.8/5(6.022 x 1023)
• molecules with a higher solubility spend longer in mobile phase.will be carried further
• Ionic lattices have a higher melting and boiling point than simple covalent molecules
• simple covalent molecules are non metals
• Gold foil experiment

  Proved plum pudding model was wrong

  Positively charged alpha particles shot at thin sheet of gold

  Expected particles to go straight through and some to be slightly deflected

  More than expected were deflected, and some backwards. Meant theres a nucleus at the center
• covalent bonds

  Strong bonds, a pair of electrons shared between two atoms

  Simple molecular structures made with a few atoms held with covalent bonds
• Simple molecular structures

  strong bonds, weak intermolecular forces

  low melting point

  dont conduct
• Giant covalent structures

  Strong covalent bonds

  High melting point

  Don't conduct except for graphite/graphene

  Aren't soluble
• Diamond

  four bonds

  strong bonds, high m.p

  rigid lattice structure - hard, strengthens tools

  doesnt conduct
• Graphite

  sheets of hexagons

  three bonds

  has layers held together weakly so can move

  soft and slippery - lubricating material

  high m.p

  can conduct
• Graphene

  single layer of graphite

  one atom thick

  high m.p

  can conduct

  can become a nanotube - strong and lightweight
• Metallic bonding

  outer shell of the metals electrons are delocalised.

  strong electrostatic attraction between positive metal ions and negative electrons

  Strong bonding

  strong forces

  lots of energy to be broken - high m.p

  insoluble

  can conduct