HOMOLGOUS SERIES (a family of organic compounds) Can you recall these functional groups from GCSE? C n H 2n+2 C n H 2n C n H 2n+1 OH RCOOH RCOOR

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1 Organic Chemistry Sixth Form Induction 1. To recognise the main functional groups and the chemical bonds they contain. To begin using IUPAC naming of straight chain and branched alkanes. (E) 2. To be describe the main reactions of alkanes, including combustion and free radical substitution (including all the three steps involved). To learn some of the key definitions (C) 3. To be able to draw the mechanism for free radical substitution of alkanes with halogens, using curly arrows for the initiation step. (A)

2 HOMOLGOUS SERIES (a family of organic compounds) Can you recall these functional groups from GCSE? C n H 2n+2 C n H 2n C n H 2n+1 OH RCOOH RCOOR

3 Some more. RCOR Ketone RCOH Aldehyde RCOCl Acyl chloride RX Halogenoalkane (x = any halogen) RNH 2 Amine RCONH 2 Amide We will leave Arenes until Year 13.

4 Some IUPAC Nomenclature The International Union of Pure and Applied Chemistry. Alkanes can be Aliphatic, i.e. straight chains or branched. The can also be Alicyclic (in rings) or Aromatic/Arenes (derived from benzene). Strain Chain Alkanes: Prefix Meth Eth Prop Suffix ane

5 STRUCTURAL ISOMERS Species with the same molecular formula but different structural formulas; e.g. Molecular formula: C 6 H 14 Different displayed formulas in the picture shown (notice the H atoms aren t shown).

6 Branches alkanes lower m.pt/b.pt Name branches first, then the parent chain (the longest chain):

7 Skeletal Formula A simpler way of representing alkanes:

8 Alkanes How do they react when heated in the presence of oxygen? Combustion Complete: CO 2 and H 2 O Incomplete CO, C and H 2 O Can we do anything else with them?

9 Substitution reactions Substitute a hydrogen for a halogen: What is a Halogen? Why do we do this? What can they be used for? What are the conditions required? UV light What type of bond breaking occurs? Homolytic fission What type of mechanism is this? Free radical What is a free radical? A species with an unpaired electron.

10 Mechanism for Free Radical Substitution of alkanes to form chlorinated alkanes.

11 Using curly arrows During homolytic fission each atom involved in the bond keeps one of the shared electron pair in the bond that breaks. This is shown using half-curly arrows: You usually only use half-curly arrows in the initiation step (minimum). Although only use curly arrows when instructed to do so in the question. These arrows show the movement of one electron. As shown here:

12 This is how you use curly arrows in propagation steps and one termination step:

13 Demonstrate 1. What functional group are these? (3 marks) a) RCOH b) RX c) RNH 2 2. Use IUPAC to name these alkanes. (3 marks) a) CH 3 CH 2 CH 2 CH 2 CH 3 b) CH 3 CH(CH 3 ) CH 2 CH 3 c) CH 3 CH(CH 3 ) CH(CH 3 )CH 3 3. What are the products when butane is heated with excess oxygen? (1 mark) 4. Write a balanced symbol equation for the above reaction. (2marks) 5. What type of reaction and mechanism occurs when methane is reacted with Chlorine in the presence of UV light? (2 marks) 6. What are the three steps in the reaction mentioned in question 5? (1 mark) 7. Draw a mechanism for the reaction of methane and chlorine in the presence of UV light using curly arrow for the first step only. Show at least 2 propagation steps. (4 marks)

14 Answers 1. What functional group are these? (1 mark each) a) Aldehyde b) Halogenoalkane c) Amine 2. Use IUPAC to name these alkanes. (1 mark each) a) Pentane b) 2-methylbutane c) 2,3-dimethylbutane 3. CO 2 and H 2 O (1 mark for both) 4. C 4 H ½O 2 4CO 2 + 5H 2 O (1 mark for correct products and one for balancing) 5. Mechanism = Free-radical (1 mark) Reaction = substitution (1 mark) 6. Initiation, propagation and termination (1 mark for each)

15 Question 7 Initiation step with arrows correctly drawn (1 mark). hµ not required. Two propagation steps are required ( 1 mark for each): You are not required to draw all bonds. Any one of these termination steps (1 mark)

16 Summer Homework 1 Revision to prepare for Test 1: Using your Periodic Table to identify the correct number of sub-atomic particles in atoms (GCSE). To understand how the modern day Periodic Table is constructed in terms of the protons and electrons (GCSE). Drawing dot-cross diagrams to represent the bonding of ionic compounds for simple covalent molecules (GCSE). Metallic Bonding (GCSE). ph scale (KS3 and GCSE). Titration procedure (GCSE) Calculating concentrations of unknown solutions (TRIPLE GCSE) Flame testing of Cations (TRIPLE GCSE) Constructing and balancing symbol equations (GCSE). Calculating Empirical Formula using data provided. (GCSE) Endothermic and Exothermic reactions and how catalysts work (GCSE). Fractional Distillation of alkanes (GCSE). Chemical test for alkanes and alkenes (GCSE). Drawing polymer repeating units for addition polymerisation (TRIPLE GCSE). Calorimetry experiments and calculating the energy changes in reactions from experimental data (GCSE & Taster Session) Hess s Lass and using Hess Cycles to calculate Enthalpy of Formation or Combustion (Will be covered in first two weeks of Year 12 to Bridge the Gap with GCSE Chemistry). IUPAC naming of Alkanes (Induction Session) Combustion reactions of alkanes (GCSE, and Induction Session) Free-radical substitution reactions of alkanes with halogens to form halogenoalkanes, including drawing a mechanism for the reaction using half-curly arrows (Induction Session).

17 Summer Homework 2 An Introduction to Mass Spectrometry: Background: Mass Spectrometry was introduced as part of the GCSE Chemistry 2 unit. At GCSE you needed to know it was used to identify a substance by its Molecular mass by looking for the Molecular ion peak (Higher Tier). During our first year of A Level Chemistry we will start to look at Mass Spectrometry in more detail. As we go through the course we will continue to expand on the interpretation of the spectra produced. For this homework exercise we will only be looking at simple analysis of Mass Spectra, not the detailed analysis using fragmentation patterns. The content you need to read up on over summer is detailed below. The whole purpose of this exercise is to challenge you to become an independent learner, which is an essential skill for success at A Level.

18 TASK To create a set of revision notes to cover the following aspects of the New A Level Chemistry syllabus: To be able to define the terms relative isotopic mass and relative atomic mass, based on the 12 C scale. To understand the terms relative molecular mass and relative formula mass, including calculating these values from relative atomic masses. To be able to analyse and interpret data from a mass spectrum to calculate relative atomic mass from relative abundance of isotopes and vice versa. To understand how mass spectrometry can be used to determine the relative molecular mass of a molecule, including organic molecules, (limited to the m/z value for the molecular ion, M +, giving the relative molecular mass of the molecule).

19 Resources you can use Future study of Mass Spectrometry Later on in the course we will look at using data from a mass spectrum to suggest possible structures of a simple organic compound from the m/z of the molecular ion and fragmentation patterns. However, this is not required for this task and will not be included in your September assessment. You do not need to be able to explain how the mass spectrometer works! Useful web links for Mass Spectrometry for A Level Chemistry: (optional for more detail)