ighalogenspp.ppt - knockhardy

GROUP VIIGROUP VIIThe HalogensThe Halogens

A guide for A guide for iiGCSE studentsGCSE students

KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING2010 2010

SPECIFICATIONSSPECIFICATIONS

GROUP VIIGROUP VII

INTRODUCTIONThis Powerpoint show is one of several produced to help students understand selected GCSE Chemistry topics. It is based on the requirements of the AQA specification but is suitable for other examination boards.

Individual students may use the material at home for revision purposes and it can also prove useful for classroom teaching with an interactive white board.

Additional Powerpoints, and the full range of AS and A2 Chemistry topics, are available from the KNOCKHARDY WEBSITE at...

www.knockhardy.org.uk

All diagrams and animations in this Powerpoint are original and created by Jonathan Hopton. Permission must be obtained for their use in any commercial work.

CONTENTSCONTENTS• Introduction

• Group trends

• Group similarities

• Reaction with metals

• Displacement reactions

• Summary

• Quick quiz

• Hydrogen chloride or hydrochloric acid?

GROUP VIIGROUP VII

INTRODUCTIONINTRODUCTION

F

Cl

Br

I

At

THE HALOGENS OCCUR IN GROUP VII OF THE PERIODIC TABLE

Group 1 2 3 4 5 6 7

0

INTRODUCTIONINTRODUCTION

F

Cl

Br

I

At

THE HALOGENS OCCUR IN GROUP VII OF THE PERIODIC TABLE

THEY ARE NON-METALS AND HAVE ELECTRONIC CONFIGURATIONS JUST ONE ELECTRON SHORT OF THE NEAREST NOBLE GAS

Group 1 2 3 4 5 6 7

0

GROUP PROPERTIESGROUP PROPERTIES

GENERAL • non-metals• exist as separate diatomic molecules… eg Cl2• have seven electrons in their outer shells• form negative ions with a 1- charge• reaction with metals and halides

GROUP PROPERTIESGROUP PROPERTIES

GENERAL • non-metals• exist as separate diatomic molecules… eg Cl2• have seven electrons in their outer shells• form negative ions with a 1- charge• reaction with metals and halides

TRENDS • appearance • boiling point

• electronic configuration• atomic size• ionic size• reactivity

GROUP TRENDSGROUP TRENDS


F2

YellowCl2

GreenBr2

Red/brownI2

GreyGAS GAS LIQUID SOLID

ColourState (at RTP)

APPEARANCEAPPEARANCE

Yellow Green Red/brown PurpleVapour colour


INCREASES down Group because more energy is required to separate the larger molecules.

F2

YellowCl2

GreenBr2

Red/brownI2

GreyGAS GAS LIQUID SOLID

ColourState (at RTP)

APPEARANCEAPPEARANCE

BOILING POINTBOILING POINT

F2

- 188Cl2- 34

Br2

58I2

183Boiling point / °C

Yellow Green Red/brown PurpleVapour colour


• electrons go into shells further from the nucleus

F Cl Br I

2,7 2,8,7 2,8,18,7 2,8,18,18,7Configuration

ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION

9 17 35 53Atomic Number


F Cl Br I

ATOMIC & IONIC RADIUSATOMIC & IONIC RADIUS

0.064 0.099 0.111 0.128Atomic radius / nm

NOT TO SCALE


ATOMIC RADIUS INCREASES down Group

IONIC RADIUS INCREASES down Group

• the greater the atomic number the more electrons there are these go into shells increasingly further from the nucleus

• ions are larger than atoms - the added electron repels the others so radius gets larger

F Cl Br I

ATOMIC & IONIC RADIUSATOMIC & IONIC RADIUS

0.064 0.099 0.111 0.128Atomic radius / nm

F¯ Cl¯ Br¯ I¯0.136 0.181 0.195 0.216Ionic radius / nm

GROUP SIMILARITIESGROUP SIMILARITIES

GROUP SIMILARITIESGROUP SIMILARITIES

• all the atoms have seven electrons in their outer shell

• ions are larger than atoms - the added electron repels the others so radius gets larger

ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION

F Cl Br I

2,7 2,8,7 2,8,18,7 2,8,18,18,7Configuration9 17 35 53Atomic Number

GROUP GROUP SIMILARITIESSIMILARITIES

MOLECULAR FORMULAMOLECULAR FORMULA

F Cl Br I

Covalent Covalent Covalent CovalentBondingF2 Cl2 Br2 I2Molecular formula

NOT TO SCALE

• all exist as diatomic molecules


ION FORMATIONION FORMATION

F Cl Br I

ConfigurationIon F¯ Cl¯ Br¯ I¯

2,8 2,8,8 2,8,18,8 2,8,18,18,8

• all gain one electron to form a negative ion of charge 1-

• ions are larger than atoms

• the smaller the atom the easier it forms an ion


ION FORMATIONION FORMATION

F Cl Br I

ConfigurationIon F¯ Cl¯ Br¯ I¯

2,8 2,8,8 2,8,18,8 2,8,18,18,8

• all gain one electron to form a negative ion of charge 1-

• ions are larger than atoms

• the smaller the atom the easier it forms an ion

REACTIVITYREACTIVITY

F Cl Br IReactivity Increasingly reactive

• reactivity decreases down the Group / increases up the Group

REACTIONS OF HALOGENSREACTIONS OF HALOGENS

1. WITH METALS1. WITH METALS

2. WITH HALIDES2. WITH HALIDES

REACTION OF HALOGENS WITH METALSREACTION OF HALOGENS WITH METALS


HALOGENS REACT WITH METALS TO PRODUCE METAL HALIDES.



THE EASE OF REACTION DECREASES DOWN THE GROUP F > Cl > Br > I




THIS IS BECAUSE ‘THE LARGER THE HALOGEN ATOM, THE LESSEASILY IT ATTRACTS THE ELECTRON IT NEEDSTO FILL ITS OUTER SHELL’




THIS IS BECAUSE ‘THE LARGER THE HALOGEN ATOM, THE LESSEASILY IT ATTRACTS THE ELECTRON IT NEEDSTO FILL ITS OUTER SHELL’

THE HALIDES OF GROUP I ARE… WHITE IONIC SOLIDSVERY SOLUBLE IN WATER

SODIUM CHLORIDE (NaCl) IS A TYPICAL GROUP I HALIDE

REACTION WITH ALKALI METALSREACTION WITH ALKALI METALS

REACTION WITH ALKALI METALS - EquationsREACTION WITH ALKALI METALS - Equations

SODIUM CHLORINE SODIUM CHLORIDE+


Na + Cl2 NaCl

SODIUM CHLORINE SODIUM CHLORIDE


Na + Cl2 NaCl


The equation doesn’t balance - multiply the formulae until it does


2Na + Cl2 2NaCl

Na + Cl2 NaCl


Balanced equation

Cl

SODIUM ATOM2,8,1

Na

CHLORINE ATOM2,8,7

11 protons; 11 electrons 17 protons; 17 electrons

SODIUM CHLORIDE FORMATIONSODIUM CHLORIDE FORMATION

Cl

SODIUM ION2,8

Na

CHLORIDE ION2,8,8

both species now have ‘full’ outer shells; ie they have the electronic configuration of a noble gas

+

11 protons; 10 electrons 17 protons; 18 electrons


Cl

SODIUM ION2,8

Na

CHLORIDE ION2,8,8

Na Na+ + e¯2,8,1 2,8

ELECTRON TRANSFERRED

Cl + e¯ Cl¯2,8,7 2,8,8

+


DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS


HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED



THIS DECREASE IN REACTIVITY DOWN THE GROUP CAN BE DEMONSTRATED USING DISPLACEMENT REACTIONS...

A DISPLACEMENT REACTION IS WHERE ONE SPECIES TAKES THE PLACE OF ANOTHER IN A COMPOUND.



THIS DECREASE IN REACTIVITY DOWN THE GROUP CAN BE DEMONSTRATED USING DISPLACEMENT REACTIONS...

A DISPLACEMENT REACTION IS WHERE ONE SPECIES TAKES THE PLACE OF ANOTHER IN A COMPOUND.

THE REACTIONS ARE EXAMPLES OF REDOX REACTIONS


SODIUMCHLORIDESOLUTIONColourless

SODIUMBROMIDESOLUTIONColourless

SODIUMIODIDE

SOLUTIONColourless

CHLORINEWATER

Pale green

BROMINEWATEROrange

A SOLUTION OF THE HALOGEN IS ADDED TO A SOLUTION OF A HALIDE

HALIDES ARE SALTS FORMED BETWEEN ELEMENTS AND HALOGENS



SODIUMIODIDE

SOLUTIONColourless

CHLORINEWATER

Pale green

BROMINEWATEROrange


NO VISIBLE REACTION

Experiment 1



SODIUMIODIDE

SOLUTIONColourless

BROMINEWATEROrange

CHLORINEWATER

Pale green


BROMINE produced

Experiment 2




BROMINEWATEROrange

CHLORINEWATER

Pale green

SODIUMIODIDE

SOLUTIONColourless

IODINE produced

Experiment 3



SODIUMIODIDE

SOLUTIONColourless

CHLORINEWATER

Pale green

BROMINEWATEROrange


NO VISIBLE REACTION

Experiment 4



SODIUMIODIDE

SOLUTIONColourless

CHLORINEWATER

Pale green

BROMINEWATEROrange


NO VISIBLE REACTION

Experiment 5




CHLORINEWATER

Pale green

BROMINEWATEROrange

SODIUMIODIDE

SOLUTIONColourless

IODINE produced

Experiment 6

SODIUM CHLORIDE

CHLORINE

SODIUM BROMIDE SODIUM IODIDE

Solution stays colourless

NO REACTION

Solution goes from colourless to orange-

yellowNO REACTION


yellowBROMINE FORMED


yellowNO REACTION

Solution goes from colourless to redIODINE FORMED

BROMINE


redIODINE FORMED

DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENSSUMMARY OF OBSERVATIONS

1

65

2 3

4

The colour change in Experiments 4 and 5 is due to dilution – there is no reaction

CHLORINE + SODIUM BROMIDE

CHLORINE + SODIUM IODIDE BROMINE + SODIUM IODIDE

DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENSEQUATIONS

CHLORINE + SODIUM BROMIDE BROMINE + SODIUM CHLORIDE

CHLORINE + SODIUM IODIDE IODINE + SODIUM CHLORIDE BROMINE + SODIUM IODIDE IODINE + SODIUM BROMIDE





Cl2(aq) + NaBr(aq) —> Br2(aq) + NaCl(aq)

The equation doesn’t balance - multiply the formulae until it does




Cl2(aq) + 2NaBr(aq) —> Br2(aq) + 2NaCl(aq)

Cl2(aq) + NaBr(aq) —> Br2(aq) + NaCl(aq)




Cl2(aq) + 2Br¯(aq) —> Br2(aq) + 2Cl¯(aq)

Cl2(aq) + 2NaBr(aq) —> Br2(aq) + 2NaCl(aq)

IONIC EQUATION




Cl2(aq) + 2I¯(aq) —> I2(aq) + 2Cl¯(aq)

Cl2(aq) + 2NaI(aq) —> I2(aq) + 2NaCl(aq)

IONIC EQUATION




Br2(aq) + 2I¯(aq) —> I2(aq) + 2Br¯(aq)

Br2(aq) + 2NaI(aq) —> I2(aq) + 2NaBr(aq)

IONIC EQUATION



THIS SHOWS THAT A MORE REACTIVE HALOGEN WILL DISPLACEA LESS REACTIVE ONE FROM AN AQUEOUSSOLUTION OF ITS SALT

DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENSSUMMARY



THIS SHOWS THAT A MORE REACTIVE HALOGEN WILL DISPLACEA LESS REACTIVE ONE FROM AN AQUEOUSSOLUTION OF ITS SALT

HOWEVER, THIS REACTION DOES NOT TAKE PLACE

BROMINE + SODIUM CHLORIDE CHLORINE + SODIUM BROMIDE

(Bromine is below chlorine in the Group so is less reactive)


PRESS THE SPACE BAR TO SEE WHAT HAPPENS

DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENSEXPLANATION

17+

CHLORINE ATOM17 PROTONS

17 ELECTRONS2,8,7

35+

BROMIDE ION35 PROTONS

36 ELECTRONS2,8,18,8

THE CHLORINE ATOM PULLS AN ELECTRON OUT OF THE OUTER SHELL OF THE BROMIDE ION – THE CHLORINE ATOM BECOMES A CHLORIDE ION AND THE BROMIDE ION BECOMES A BROMINE ATOM.

BECAUSE BROMINE ATOMS ARE LARGER THAN CHLORINE ATOMS, IT IS EASIER TO PULL ONE OF THEIR OUTER SHELL ELECTRONS OUT.

CHLORINE NOW HAS THE OUTER SHELL ELECTRONIC CONFIGURATION OF A NOBLE GAS.

DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENSEXPLANATION

CHLORINE ATOM17 PROTONS

17 ELECTRONS

BROMIDE ION35 PROTONS

36 ELECTRONSCHLORIDE ION17 PROTONS

18 ELECTRONS

BROMINE ATOM35 PROTONS

35 ELECTRONS

DISPLACEMENT REACTIONS OF HALOGENS - DISPLACEMENT REACTIONS OF HALOGENS - REDOXREDOX

A REDOX REACTION INVOLVES BOTH OXIDATION AND REDUCTION



REDUCTION IS THE… GAIN OF ELECTRONS

OXIDATION IS THE… REMOVAL OF ELECTRONS





IN THE REACTION BETWEEN CHLORINE AND SODIUM BROMIDE, CHLORINE ATOMS PULL ELECTRONS OUT OF BROMIDE IONS.


Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)





THE BROMIDE IONS ARE OXIDISED… ELECTRONS ARE REMOVED


Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)OXIDISED

ELECTRONSREMOVED

CHLORINE IS THE OXIDISING AGENT





THE BROMIDE IONS ARE OXIDISED… ELECTRONS ARE REMOVEDTHE CHLORINE ATOMS ARE REDUCED… ELECTRONS ARE GAINED


Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)REDUCED

GAIN OF ELECTRONS

BROMIDE ION IS THE REDUCING AGENT





THE BROMIDE IONS ARE OXIDISED… ELECTRONS ARE REMOVEDTHE CHLORINE ATOMS ARE REDUCED… ELECTRONS ARE GAINED


Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)REDUCED OXIDISED

ELECTRONSREMOVED

GAIN OF ELECTRONS

OXIDISING POWER OF HALOGENSOXIDISING POWER OF HALOGENS


THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY




F Cl Br I


0.064 0.099 0.111 0.128Atomic radius / nm

---- DECREASING OXIDISING POWER ----->




F Cl Br I


0.064 0.099 0.111 0.128Atomic radius / nm

THE SMALLER THE HALOGEN, THE LESS SHIELDING THERE IS AND THE GREATER THE EFFECTIVE PULL OF THE NUCLEUS.





F Cl Br I


0.064 0.099 0.111 0.128Atomic radius / nm


THE GREATER THE PULL OF THE NUCLEUS, THE EASIER THE ATOM CAN PULL AN ELECTRON OUT OF ANOTHER SPECIES.





F Cl Br I


0.064 0.099 0.111 0.128Atomic radius / nm


THE GREATER THE PULL OF THE NUCLEUS, THE EASIER THE ATOM CAN PULL AN ELECTRON OUT OF ANOTHER SPECIES.

CONSEQUENTLY, THE BIGGER THE ATOM, THE EASIER AN ELECTRON CAN BE REMOVED.


SYMBOL

MOLECULAR FORMULA

APPEARANCE

STATE (room temp)

F

PALE YELLOW

GAS

Cl

FLUORINE IODINE

ELECTRONIC CONFIGURATION

BOILING POINT

2,7

INCREASES

2,8,7

GAS

ION(electronic config)

F¯2,8

Cl¯2,8,8

REACTION WITH SODIUM LESS REACTIVE

PRODUCT OF REACTION WITH SODIUM

SODIUM FLUORIDE (NaF)

SODIUM CHLORIDE (NaCl)

PALE GREEN

Br I

BROMINECHLORINE

F2 Cl2 Br2 I2

RED-BROWN GREY-BLACK

LIQUID SOLID

2,8,18,7 2,8,18,18,7

Br¯2,8,18,8

I¯2,8,18,18,8

SODIUM BROMIDE (NaBr)

SODIUM IODIDE (NaI)

GROUP VII - SUMMARYGROUP VII - SUMMARY

COLOUR OF VAPOUR PALE YELLOW GREEN RED-BROWN PURPLE

QUICK QUIZQUICK QUIZ

1. ELEMENTS IN GROUP 7 ARE KNOWN AS THE ………2. WHAT ARE THE NAMES OF THE ELEMENTS3. HOW DOES THE ATOMIC NUMBER CHANGE DOWN THE GROUP?4. HOW DOES THE ELECTRONIC CONFIGURATION CHANGE?5. HOW DOES THE ATOMIC SIZE (RADIUS) CHANGE?6. HOW MANY ELECTRONS DO THEY HAVE IN THE OUTER LEVEL?7. ARE THEY METALS OR NON-METALS?8. WHAT HAPPENS TO THEIR COLOUR DOWN THE GROUP?9. DO THEY GO AROUND IN PAIRS OR AS MONATOMIC GASES?10. WHAT HAPPENS TO THEIR STATE AT ROOM TEMPERATURE?11. WHAT TYPE OF COMPOUNDS DO THEY FORM WITH METALS?

12. HOW CAN EXPLAIN THEIR RELATIVE REACTIVITY IN TERMS OF THE ATOMIC STRUCTURE?

QUICK QUIZ - ANSWERSQUICK QUIZ - ANSWERS

1. HALOGENS.2. FLUORINE, CHLORINE, BROMINE, IODINE, ASTATINE.3. ATOMIC NUMBER INCREASES DOWN THE GROUP.4. GET MORE SHELLS DOWN THE GROUP.5. ATOMIC SIZE INCREASES DOWN THE GROUP.6. THEY ALL HAVE SEVEN ELECTRONS IN THE OUTER LEVEL.7. THEY ARE NON-METALS.8. COLOUR DARKENS DOWN THE GROUP.9. ATOMS GO AROUND IN PAIRS OR AS DIATOMIC GASES.10. GO FROM GAS TO SOLID DOWN THE GROUP.11. THEY FORM IONIC COMPOUNDS WITH METALS.12. THE LARGER THEY ARE THE LESS EASILY ELECTRONS ARE GAINED

AND THE LESS REACTIVE THEY BECOME.

HYDROGEN CHLORIDE OR HYDROCHLORIC ACID? HYDROGEN CHLORIDE OR HYDROCHLORIC ACID?


Hydrogen chloride is a colourless covalent gas; it is a poor conductor of electricity because there are no free electrons or ions present. It has no action on dry litmus paper because there are no aqueous hydrogen ions present.


In water, the hydrogen chloride molecules dissociate into ions. The solution now conducts electricity showing ions are present. For each hydrogen chloride molecule that dissociates (splits up) one hydrogen ion and one chloride ion are produced. The solution turns litmus paper red because of the H+(aq) ions.


HYDROGEN CHLORIDE HYDROCHLORIC ACID

colourless gas Appearance colourless soln. covalent molecule Bonding aqueous ions

HCl(g) Formula HCl(aq) poor Conductivity goodno reaction Dry blue litmus goes red


HCl(g) —> H+ (aq) + Cl¯(aq)

Hydrogen chloride dissociates in water because water is a polar solvent. However, when hydrogen chloride is placed in an organic solvent such as methylbenzene it does not dissociate and does not produce H+ ions.

WATERA polar solvent

Molecules dissociateThe solution turns litmus paper red because of the H+(aq) ions.

DOES HYDROGEN CHLORIDE ALWAYS DISSOCIATE?DOES HYDROGEN CHLORIDE ALWAYS DISSOCIATE?

METHYLBENZENEA non-polar solvent

NO dissociationThe solution does not litmus paper red because there are NO H+(aq) ions.

WATER IS A POLAR SOLVENT – it has one end which is slightly positive and another end which is slightly positive.

WHY DOES HYDROGEN CHLORIDE DISSOCIATE IN WATER?WHY DOES HYDROGEN CHLORIDE DISSOCIATE IN WATER?

positive end

negative end



When a molecule of hydrogen chloride is put into water, the water molecules ‘encourage’ the covalent bond holding the hydrogen and chlorine atoms together to split, thus forming ions.

positive end

negative end



The chloride ions are attracted to the slightly positive hydrogen end of water. The slightly negative oxygen end of water attracts the H+ ions.

When a molecule of hydrogen chloride is put into water, the water molecules ‘encourage’ the covalent bond holding the hydrogen and chlorine atoms together to split, thus forming ions.



positive end

negative end

GROUP VIIGROUP VIIThe HalogensThe Halogens

THE ENDTHE END

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ighalogenspp.ppt - knockhardy

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