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Which is the odd one out?

Learn about the nomenclature, reactions, and physical properties of halogenoalkanes in this informative lesson. Explore reaction mechanisms and conduct experiments to understand the behavior of these compounds. Gain insight into the influence of bond polarity and bond enthalpy on the reactivity of halogenoalkanes. Review the impact of CFCs and their role in environmental issues. This lesson prepares you for understanding nucleophilic substitution reactions.

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Which is the odd one out?

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  1. Bell work Which is the odd one out?

  2. Manufacturing Ions in solution Ionic Formulae Halogenoalkanes Big Picture Redox Bonding Atoms and Ions Halogens Dipoles Elements of the sea

  3. Learning Outcomes ContentProcessBenefit • Nomenclature of halogenoalkanes • Physical and chemical reactions of halogenoalkanes including hetrolytic fission • Carry out an experiment • Explain reaction mechanisms

  4. New Information Nomenclature Homologous series (actually one for each halogen!) • Location of halogen (smallest possible) • Prefix of halogeno – with an o (i.echloro/flouro/bromo – if more than 1 – alphabetically) • Root is parent C chain

  5. Activity Name these/draw these CHCl3 2,3-dichloropentane 3-bromobut-1-ene 2,3-dibromo-1-chloro-2-methylbutane

  6. New Information Physical properties Halogen makes gp polar – but not sufficient to make it miscible with H2O Complete this worksheet • Explain the physical properties if astatine was attached. Extension Task

  7. New Information Chemical Reactions • Try to break Hal-C bond (hal short for halogen) • Bond breaking (fission) can be either hetrolytic or homolytic. H3C-Cl • Guess what do you think they mean?

  8. Homolytic fission • Can occur by visible/UV radiation (hv) hv + H3C + Cl H3C Cl • Each of the bonding e- goes to each of the atom. • Creating a highly reactive atom/gp of atoms with an unpaired e- are called a radicals. • This causes ozone issues in stratosphere HOT question Should there be a charge here?

  9. Heterolytic fission • Reactions depend on conditions (non-polar solvent/gas phase with high temp homolytic fission) • Common in lab conditions (polar solvent) H3C Cl HOT question Give an example of a polar solvent H3C + Cl • Both of the bonding e- goes to one of the atom/groups of atoms. • Forms a –ive halide ion and a +ivecarbocation (carbon + ca+ion).

  10. Activity ES 6.2 • Do these Hal-C bonds break at the same time? • Remember to answer the questions.

  11. Demonstrate ES 4.5 If a precipitate appears, this means that hydrolysis has taken place – the carbon–halogen bond has broken and halide ions have been released from the halogenoalkane. 1. Which halogenoalkane underwent the fastest hydrolysis? • Which was slowest? 2. Student X suggests that the rate of hydrolysis depends on the polarity of the C–Hal bond, and that the halogenoalkane with the most polar bond will hydrolyse most quickly. • Student Y suggests that the rate of hydrolysis depends on the strength of the C–Hal bond, and that the halogenoalkane with the weakest bond will hydrolyse most quickly. • Use your Data Sheets to find data that you think will help • you and write it down. Use the data to decide whether • bond polarity or bond enthalpy is more important in • determining the relative reactivity of halogenoalkanes. 3. What result would you predict for 1-fluorobutane? Explain your answer. 4. Why was this experiment done using halogenobutanes rather than halogenomethanes? Which Which is more important in reactivity of halogenoalkanes bond enthalpy or bond polarity? Extension – predict how would fluorobutane react?

  12. Demonstrate ES 4.5 Enthalpy more influential – so fluoroalkane would happen slower/less reactive than chloroalkane as higher bond enthalpy for fluroalkane. • Remember to answer the questions.

  13. Review CFCs CFC’s release – hang around in the troposphere and then .......

  14. Review CFCs

  15. Home Learning Complete ES6.2 Read 13.1 and make notes – we will cover nucleophilic substitution but reading ahead will help you understand it better.

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