AS Chemistry - OCR - F321

AS Chemistry - OCR - F321

1. Electronic Structure, Periodic Table and Structure of the Atoms & Isotopes

   • Inside an atom
     • Neutron
     • Proton
     • Electron
   • Definitions
     • Must learn these!
     • Molecule - How elements come together to complete their outer shell
     • Ion - An atom with a charge (+/-)
     • Element - Found on the periodic table
     • Mixture - 2 or more substances together which haven't reacted
     • Compound - Same as a mixture but a reaction has taken place
     • Atom - The smallest part of an element that keeps its chemical properties
     • THE RELATIVE ISOTOPIC MASS IS THE MASS OF THE ISOTOPE COMPARED TO 1/12 OF THE MASS OF AN ATOM OF CARBON-12
     • THE FIRST IONISATION ENERGY IS THE ENERGY REQUIRED TO REMOVE ONE ELECTRON FROM EACH ATOM IN 1 MOLE OF GASEOUS ATOMS TO FORM 1 MOLE OF GASEOUS 1+ IONS
   • Rules:
     • Molecules = Non-metals
     • + Ions = Metals
     • - Ions = Non-metals
     • Molecular ions = don't follow these rules
       • Must learn these
   • Isotopes
     • Same number of PROTONS & ELECTRONS
     • Different number of NEUTRONS
   • Arrangement of Electrons in an Atom
     • Atomic Orbitals
       • s
         • Only need this one and p
         • Spherical
       • p
         • Only need this one and s
         • Dum bell shaped
         • 3 make a sub-shell
       • d
       • f
       • Each orbital can hold a max. of 2 electrons
   • Points That Affect Ionisation Energy
     • Nuclear Charge
       • Larger charge - more energy needed
     • Shielding
       • More shielding - less energy needed
     • Distance From the Nucleus
       • Further from the nucleus - less energy needed

2. Oxidation Numbers

   • OXIDATION IS LOSS (of electrons)
   • REDUCTION IS GAIN (of electrons)
   • Oxidation is the addition of oxygen
   • Oxidation is an increase in the oxidation number
   • CO2 - OxNo: +4 -2
   • Group 1 - OxNo: +1
   • Group 2 - OxNo: +2
   • Element - OxNo: 0
   • Flourine & Oxygen - OxNo: +2
   • Redox Reactions
     • Reduction and oxidation
       • Both occur but to different elements
       • Disproportionation Reaction
         • Both occur to the SAME element
   • Oxidation agent - gains electrons
   • Reduction agent - loses electrons

3. Groups 2 & 7

   • GROUP 2
     • Properties
       • High melting points
       • High boiling points
       • Low densities
       • Colourless compounds formed
     • Giant metallically bonded (See bonding section)
     • React by losing 2 electrons from their outer shell to the "sea of delocalised electrons"
   • GROUP 7
     • Halogens
       • Flourine
       • Chlorine
       • Bromine
       • Iodine
       • Astatine
     • Colours
       • Cl2(g)
         • Element - pale yellow
         • In H2O - pale yellow
         • In cyclohexane - yellow
       • Br2(l)
         • Element - orange
         • In H2O - orange
         • In cyclohexane - dark orange
       • I2(s)
         • Element - grey
         • In H2O - red/brown
         • In cyclohexane - purple
     • If the halogen is more reactive than the halogen in the compound, it will be displaced

4. Moles Calculations

   • Avogadro's Constant = 6.02 x 10^23
   • MASS OF A SUBSTANCE WHICH HAS THE SAME NUMBER OF PARTICLES AS IN 12g OF CARBON-12
   • Moles = mass(g) / molar mass
     • n = m/Mr
   • Moles
     • Ratio
       • Whatever
   • Empirical formula
     • Find the molar ratio
       • Divide by the smallest number
   • Molecular formula
     • Empirical formula mass
       • Number of units in a molecule
   • 1dm^3 = 1000 cm^3
   • Volume (gas) = moles x 24
   • concentration = moles / volume
   • Volume (solution) = moles / concentration
   • Molar mass = mass / moles
   • No. of atoms = moles x (6.02 x 10^23)

5. Acids & Bases

   • Acids
     • HCl - Strong acid
     • Ethanoic - Weak acid
     • All contain H+
     • An acid is a PROTON DONOR
   • Bases
     • A base is a PROTON ACCEPTOR
     • Can be:
       • Metal oxides
       • Metal hydroxides
         • Soluble in water
         • Produce OH-
         • pH > 7
       • Metal carbonates
       • Ammonia
         • NH3 + H2O -> NH4OH
     • Neutralise acids
     • A SALT FORMS WHEN THE HYDROGEN ATOMS OF AN ACID ARE REPLACED BY METAL IONS OR AMMONIUM IONS

6. Bonding

   • Metallic
     • Atoms are ionised
     • + Ions are in a fixed lattice position
     • Outer shell electrons become delocalised
     • Giant lattice structure
     • Conducts electricity
     • High melting point
   • Covalent
     • Simple molecular
       • Strong covalent bonds - not broken
       • Weak IMFs
       • Low melting point
       • Low boiling point
       • Do not conduct electricity
     • Giant covalent molecular
       • Strong covalent bonds - broken
       • Found only in:
         • Carbon - Graphite
         • Carbon - Diamond
         • Silicon
       • High melting point
       • Graphite - conducts electricity
       • Diamond - does not conduct electricity
   • Ionic
     • Electrostatic attraction between oppositely charged ions
     • Giant lattice structure
     • Conduct electricity when molten or dissolved in water
     • Doesn't conduct when solid
     • High melting point
   • IMFs
     • Van der Waals'
       • Induced dipoles
       • Weakest
       • Induced dipoles
       • Constantly breaking
     • Permanent dipole
       • Medium
     • Hydrogen
       • Only found when hydrogen is bonded with:
         • Oxygen
         • Nitrogen
         • Flourine