Which is the odd one out?

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

Content Process Benefit Nomenclature of halogenoalkanes Physical and chemical reactions of halogenoalkanes including hetrolytic fission Carry out an experiment Explain reaction mechanisms

Nomenclature Homologous series (actually one for each halogen!) 1.Location of halogen (smallest possible) 2.Prefix of halogeno – with an o (i.e chloro/flouro/bromo – if more than 1 – alphabetically) 3.Root is parent C chain

Name these/draw these CHCl 3 2,3-dichloropentane 3-bromobut-1-ene 2,3-dibromo-1-chloro-2-methylbutane

Physical properties Halogen makes gp polar – but not sufficient to make it miscible with H 2 O Complete this worksheet 1.Explain the physical properties if astatine was attached.

Chemical Reactions Try to break Hal-C bond (hal short for halogen) Bond breaking (fission) can be either hetrolytic or homolytic. H 3 C-Cl Guess what do you think they mean?

Homolytic fission H 3 C 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 H 3 C + Cl Can occur by visible/UV radiation (hv) hv + HOT question Should there be a charge here?

Heterolytic fission H 3 C Cl Both of the bonding e- goes to one of the atom/groups of atoms. Forms a –ive halide ion and a +ive carbocation (carbon + ca+ion). H 3 C + Cl Reactions depend on conditions (non- polar solvent/gas phase with high temp homolytic fission) Common in lab conditions (polar solvent) HOT question Give an example of a polar solvent

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

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?

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.

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

CFCs

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