chem

• (g) 80%1
• Coordinated Sciences
• * th
• created by
• many graphics
• My Exams
• Particulate nature of matter

  • particle separation
  • arrangement (regular ? fixed ?)
  • motion
• atoms, compounds, ions


  • H
  • Mg SO4
  • A-
• Heating /cooling curve


  melting points + boiling points are unique to pure substances
• KINETIC THEORY


  • substance absorb thermal e. → K movement → structure ? motion ? → vibrates → expands → structure breaks
  • KE > intermolecular forces between 32 things
• DIFFUSION


  • states: liquid,#
  • random motion
  • requires energy ?
  • [ h_ ] → [-1 ] until evenly spread out
  • make faster ?
  • relative molecular mass (Mr)
  • faster in than
  • same to , different rates → Mr d → of
• C2. Experimental techniques
• C2.1. Measurements


  • unit
  • equipment
  • liquids 2
  • time s
  • to 0C
  • mass g. kg
  • volume cm?m3
• accuracy


  • precise: variable V
  • accurate: fixed V
• C2.2. Criteria of purity
• pure


  only one substance
• impurities


  melting and boiling point analysis
• mixtures


  melt / boil over a range of to
• Paper chromatography


  • separate substances w/ different solubilities in a solvent
  • solvent travels via capillary action (> dif rates
  • Retention factor (Rf) values → identify components of mixtures
  • compare Rf (unknown) with Rf( Known) under same conditions
  • ratio) Rf = d moved by compound ¥ ( no units )
  • d " " solvent Cmf £1
  • highest / lowest solubility ?
  • pure / impure ?

  
• C2.3. Methods of purification

  • Mixture of solids
  • Mixture of liquids: immiscible liquids
  • Filtration: decanting (pouring carefully)
  • centrifugation
  • a separating funnel
  • crystallisation: heat, cool (once cooled) → o filter to collect crystals, wash w/ cold , distilled water to remove impurities, dry
  • Simple Distillation
  • Fractional distillation

  
• C3. Atoms, elements , compounds
• compound


  pure substance, 32 elements chemically combined
• element


  unlimited #, atoms w/ same # of protons
• mixture


  32 substances NOT chemically combined, can be separated physically
• metals and non - metals

  • metals
  • non - metals
• conc


  amount of solute / specific V of solvent
• C3. Atomic structure
• NUCLEON NUMBER


  a = p + n in shells 1- 08 + -1 + + 1-
• Electron shells


  try some configurations ?
• Noble gases


  Group 0/ VII, full outer shells → unreactive = stable
• Isotopes


  atoms of same element, same proton #, dif nucleon #, same properties (same # e- in outer shell)
• Ionic bonds


  between metallic + non - metallic
• Ionic compounds


  form lattice structures: regular arrangement, alternating +ve and -ve ions
• Non - metallic elements


  form simple molecules with covalent bonds between atoms, each atom gains full outer shell
• Covalent bonds


  • Single: H2 , Cl2 , H2O , CH4 , NH3 , HCl
  • Complex (double / triple): N2 , C2H4 , CH3 OH , CO2

  
• Ionic vs covalent


  • melting/boiling pt.: ionic compounds high, simple covalent substances low
  • conductivity: ionic compounds yes in molten / solution, covalent no
  • solubility: ionic compounds yes in organic solvents, covalent no
• Macromolecules


  • allotrope: dif atomic / molecular arrangement, same element, same physical state
  • element C: giant covalent structures, tetrahedron, layers of hexagonal - shaped forms, very strong covalent bonds, 1 free e- per C, no intermolecular forces → conduct 4 ? no
  • Silicon (IV) Oxide: macromolecular, occurs naturally as sand, quartz, 10 bonds to 2 Si, 1- Si bonds to 4 Os

  
• C4. Stoichiometry
• Stoichiometry


  atoms combine → full valence shells in fixed ratios

  
• Types of chemical formulae

  • Structural formula: diagram (displayed formula), written (simplified structural formula)
  • Molecular formula: actual # of atoms
  • Empirical formula: simplest ratio