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HIGHER CHEMISTRY - Coggle Diagram

- - - - alkenes - CnH2n
      - cycloalkanes - CnH2n
      - alkanes - CnH2n+2
    - - Only carbon-carbon single = saturated
      - Contains carbon-carbon double = unsaturated
  - - - Identify and name functional groups
        
        hydroxyl functional group (OH)
        
        name ends in -anol
      - Represent alcohols in different ways
      - Classify alcohols
        
        Classification:
        
        primary alcohol - one C joined to the C bonded to the OH group
        
        secondary alcohol - 2 Cs joined to the C bonded to the OH group
        
        tertiary alcohol - 3 Cs joined to the C bonded to the OH group
      - Physical properties of alcohols
        
        All alcohols exhibit hydrogen bonding due to the presence of the highly polar hydroxyl functional group. Hydrogen bonding can be used to explain the properties of alcohols, including boiling points, melting points, viscosity and solubility/miscibility in water.
- - - - Give the definition of oxidising and reducing agents
        
        From this you must be able to identify oxidising and reducing agents from equations
        
        Oxidising agents:
        -Add Oxygen
        -Remove Hydrogen
        -Electron Donor
        
        Reducing agents:
        -Remove Oxygen
        -Add Hydrogen
        -Electron Acceptor
      - Identify oxidising and reducing agents using the electrochemical series:
        -The best reducing agents are found at the top of the electrochemical series
        -The best oxidising agents are found at the bottom of the electrochemical series.
    - - apply the rules to combine ion-electron equations
        
        Combining Simple Ion-Electron Equations
        1.Copy the Ion-Electron equations from the data booklet and
        reverse the higher equation so it represents oxidation.
        2.Make the number of electrons in the two equations equal.
        3.Cancel species which appear equally on the left and right of the arrows.
        4.Sum the remaining reactants on left and products on right.
        
        More Complex Equations:
        1.Copy the two Ion-Electron equations
        2.Balance the number of electrons in both equations by multiplication.
        3.Cancel the electrons on both sides.
        4.Cancel the H+ ions where possible- as much as possible.
        5.Cancel the water molecules where possible- as much as possible.
        6.Combine the two final equations.
      - Apply the rules for writing equations for scratch:
        1.Start with the given ions.
        2.Balance the non-oxygen symbols.
        3.Balance the oxygen symbols with water.
        4.Balance hydrogen symbols with hydrogen ions.
        5.Balance charges with electrons.
    - - describe how to make the procedure reliable:
        -Make sure all results are concordant (within 0.2 of each other).
        -Discard the first titration results as this is the rough.
      - describe how the end-point of the experiment can be determined.
        Make sure all results are concordant.
      - I can use the data generated to perform calculations
        
        (C1V1) / n1 = (C2V2) / n2
      - list the steps to make a standard solution:
        
        (A solution of accurately known concentration is known as a standard solution.)
        To prepare a standard solution you need to accurately measure the number of moles required to make the solution for the volume you require.
        You will need to know the mass in that number of moles so it can be measured on a balance.
        
        You dissolve that number of moles in a beaker with deionised water.
        
        The solution is then transferred with washings to a standard volumetric flask (like in the vitamin C titration)
        
        The flask is then accurately made up to the calibration line and thoroughly mixed by inversion of the flask.
  - - - Explain properties of Ionic/covalent substances
        
        Ionic
        
        High MP - many strong ionic bonds, only conduct when in solution or molten
        
        Covalent
        
        Low MP, never conduct
      - Describe the structure of ionic/covalent substances
        
        Ionic
        
        metals lose electrons and form positive ions
        non-metals gain electrons to form negative ions
        electrons are transferred from metals to non-metals
        
        Ionic bonding is the electrostatic force of attraction between positively and negatively charged ions and forms a lattice
        
        Covalent
        
        electrostatic attraction between a shared pair of electrons and the positively charged nuclei of the two atoms which are sharing these electrons
      - Draw outer electron diagrams for molecules
    - - Identify the type of covalent bond
        
        Polar
        
        the electron is off centre, pulled more towards the atom with the greater electronegativity
        
        Pure
        
        electrons are held in the middle as both atoms have similar electronegativities
      - explain why there are different types of covalent bond
        
        Atoms have differences in electronegativity (the attraction to a shared pair of bonding electrons) and so some molecules electrons will not be shared equally
      - Identify the type of covalent molecule
        
        Polar molecule
        
        polar covalent bond, forms a permanent dipole, Permanent dipole-Permanent dipole interactions are additional electrostatic forces of attraction between polar molecules. The fact that the dipoles are permanent means that these attractions are stronger than London dispersion forces for molecules with similar numbers of electrons, so have higher MP/BP
        
        polar molecules are affected my charged rods etc.
        
        Non-Polar molecule
        
        pure covalent bond OR symmetrical polar covalent bond, just LDFs, at room temperature, the LDFs are not able to hold the molecules together and so many non-polar molecules exist in the gas state.
    - - Describe LDF'S
        
        In NP molecules, weakest intermolecular force, cause by temporary dipole (electron cloud wobble)
      - Describe PD-PD
        
        In polar molecules, caused by a permanent dipole attraction between molecules
      - Describe Hydrogen Bonding
        
        strongest intermolecular force, caused by hydrogen being bonded to either F,O or N (greatest difference in electronegativity)
  - - - State collision theory
        
        For a chemical reaction to take place, the reactant particles must collide:
        
        with sufficient kinetic energy (activation energy)
        
        with correct geometry
      - State requirements for a successful collision
        
        Particles must have enough kinetic energy, called activation every
        
        must have correct geometry (aligned)
      - Perform calculations between reaction time and relative rate
        
        1/time - measureed in s-1
      - Describe effects on reaction rate
        
        Particle Size
        
        Exposing more surface area means more molecules can react as only particles on the surface of a sold can be involved in a reaction
        
        Concentration
        
        increasing the number of molecules in a given volume means molecules will 'bump' into one another more often so more reactions will happen per second
        
        Tempurature
        
        increasing temp is increasing the kinetic energy of the particles - this means more collisions will happen per second and they will have a higher energy making them more likely to be successful
        
        Catalyst
        
        catalysts provide an alternate route to the product with a lower activation energy so more reactants will have enough energy to react
      - Explain the importance of controlling the rate of a reaction
        
        Ensure its is fast enough to be economically viable (cost effective)
        
        Ensure it is not too fast and risk explosion
      - Describe an experiment that can be used to show concentration affects reaction rate
    - - Interpret and sketch potential energy diagrams
      - describe use key words to describe the pathway of a reaction
        
        A reaction is endothermic if more energy is released than supplied (-H)
        
        A reaction is endothermic if more energy is supplied than released (+H)
        
        activated complex is the top off the graph
        
        enthalpy change is the difference between the products and reactants
        
        activation energy is the difference between the top of the graph and the reactants potential energy
      - Calculate enthalpy changes
        
        change in enthalpy = Enthalpy(products) - Enthalpy(reactants)
        
        measured in kJ
    - - The temperature is a measure of the average kinetic energy in a system.. Some particles have more energy and some have less. This can be represented in an energy distribution diagram
        
        increasing the temperature means a greater number of particles have energy in excess of Ea - the area to the right of Ea increases
      - Total number of collisions with sufficient kinetic energy is the total area under the graph to the right of the Ea
      - increasing the concentration - area under whole graph increases - area to the right of Ea increases
      - catalysts move the Ea line to the left, increasing the total collision area
  - - - Explain the trends in atomic size across a period and down a group
        
        On going across a period, the atomic size decreases - moving from one element to the next, the atomic number (number of protons) increases but the number of energy levels stays the same which means this increasing positive charge of the nucleus pulls the electrons in the same energy level closer.
        
        Going down a group in the periodic table the atomic size increases - moving from one element down to the next, the number of occupied energy levels (electron shells) is increasing and these extra energy levels “screen” the nuclear charge from the outer electrons allowing them to move slightly further away.
      - Give the definition of atomic radius
        
        Covalent radius- half the distance between the nuclei of two identical atoms when they are joined by a single covalent bond.
    - - Give the definition and write equation to show ionisation energy
        
        The first ionisation energy of an element is the energy required to remove one electron from every atom in a mole of free gaseous atoms (kJ mol-1)
      - Explain the trends in ionisation energy across a period and down a group
        
        On going across a period, there is a general increase in first ionisation energy as increasing nuclear charge (protons in nucleus) hold the electrons more tightly
        
        On going down a group in the periodic table, the first ionisation energy decreases as the electron being removed is increasingly further from the nucleus (as a result of the increasing size of the atom) and the screening effect caused by inner electrons
    - - Give the definition of electronegativity
        
        Electronegativity is a measure of an atom's attraction for the shared pair of bonding electrons
      - Explain the trends in electronegativity across a period and down a group
        
        Across a period electronegativity increases as the charge in the nucleus increases across a period:
        greater number of protons = greater attraction for bonding electrons
        
        Down a group electronegativity decreases as atoms have a bigger radius (more electron shells) - the positive charge of the nucleus is further away from the bonding electrons and is screened by the extra electron shells
    - - State the bonding and structure found in any of the first 20 elements
        
        Covalent Network - covalently bonded atoms in a three dimensional network
        
        Very high MP and BP as e- are not free moving
        
        B, C, Si
        
        Covalent Molecular - electrostatic attraction between a shared pair of electrons and the positively charged nuclei of the two atoms which are sharing these electrons
        
        MP down - increasing - LDF's are greater
        
        N, O, F, P, S, Cl
        
        fullerenes are discrete carbon molecules - C60+ - higher MP than smaller molecules
        
        Metallic Lattice - electrostatic force of attraction between positive ions and delocalised electrons
        
        MP down - decreasing - electrons are screened, electrostatic attraction is less
        MP across - increases - increased nuclear charge, greater electrostatic attraction
        
        Li, Be, Na, Mg, K, Ca
        
        Monotomic - single atoms in a gas state, LDF's hold together
        
        BP down - increase - greater LDF's
        
        He, Ne, Ar
      - I can explain the properties of LDF and where it is found
        
        London Dispersion forces are caused by a vibration or wobbling in the electron clouds - temporary dipole
        
        LDF is the electrostatic attraction between a momentary slight charge on one atom and the momentary slight charge it causes on the neighbouring atom. The bigger the atom, the more electrons, the greater the attractive force.