VCE Chemistry Unit 1

VCE Chemistry Unit 1

1. Elements and The Periodic Table

   • Forms of the Periodic Table
     • Medeleer's Periodic table - Arranged in order of increasing atomic mass and similar chemical properties
     • The modern periodic table - Elements arranafed in increasing atomic number (no. of protons)
   • Trends in the Periodic Table
     • Atomic radius - Decrease across, Increase down
     • Electronegativity - Increase across, Decrease down
     • Ionisation energy - Increase across, decrease down
     • Reactivity of metals - increase down (easier to loose electrons)
     • Reactivity of non-metals - Decrease down (harder to loose electrons)
     • Reactions are transfers of electrons
     • Atomic radius = distance from nucleus to valence electrons
     • Electronegativity = atoms ability to attract electrons to itself
     • Schrondinger model = s,p,d,f

2. Metals

   • Metallic bonding
   • Properties of metals
     • Har and high boiling point
       • Strong electrostatic attraction forces
     • Conductive
       • Free moving delocalised electrons will move to a positve electrode
     • Ductility and malleability
       • Force applied causes metal ions to side past each other
     • Lustre
     • Conduction of heat
   • Metal structure
     • Smaller crystals = harder metal
     • Smaller crystals = more brittle
     • Structure can be altered
       • Workhardening = working cold metals causes a rearrangment of crystal grains
         • Smaller crystals = harder and more brittle
       • Alloying = metals melted and mixed with another substance they are generally harder with a lower melting point
         • Substitutional = fairly similar sized cations formed by elements with similar properties to the main metal
         • Interstitial = smaller portion of signifcantly smaller atoms added to the main metal
       • Heat treatment = casting moltern metal solidifies crystals grow, individual crystals = grains
         • Annealing = heat and cool slowly (larger crystals)
         • Quenching = heated and cooled quickly (tiny crystals)
         • Tempering = low heating and slow cooling (intermediate crystals)
     • Delocalised elctrons are located in spoecific places therfore they are unable to jump crystals during any manipulation

3. Ionic bonding = transfer of elctrons resulting in cations and anions electrostatically attracted forming ionic bonds

   • Common properties
     • Brittleness
     • Hardness
     • High melting point
     • Difference in electrical conductivity in solid vs liquid shape
   • Formation of crystals
     • Cooling rate
     • Concentration of solution
   • Hydrated ionic compounds = water molecules trapped within the ionic lattice

4. Covalent bonding = bonding where both atoms share electrons to complete their outershells

   • Molecular representation
   • VSEPR to determine the shape of molecules
     • Valence shell electron pair repulsion (VSEPR) = Outer shell electron pairs mutually repel due to their negative charge and adopt possitiions as fair from each other as possible
     • Lone pairs repel slightly more than bonding pairs
     • Double/triple bonds are treated as a single bond in this model as they must stay in the same location they don't repel
   • Electronegetivitiy and polatity
     • Polar bond = uneven distribution of charge resulting in one atom being more negative than the other
     • Intramolecular forces = forces that exist between different molecules
     • Intermolecular forces = weak , the strength of the two forms of attraction determines different properties of covalent compounds
       • Dispersion force = result of attraction between temporary dipoles. These can be random fluctuations in the distribution of electrons
       • Dipole-Dipole force = occur due to permanent dipole
         • Increased polarity the stronger the dipole-dipole forces
         • Result of the electrostatic attraction between the polar ends of polar molecfules
       • Hydrogen bonding= stronger dipole-dipole forces developed when a FON bonds with hydrogen
   • Carbon lattices
     • Allotropes = different forms of the same elements

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