Halogens

GROUP VIIGROUP VII
The HalogensThe Halogens
A guide for GCSE studentsA guide for GCSE students
KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING
20102010
SPECIFICATIONSSPECIFICATIONS

GROUP VIIGROUP VII
INTRODUCTION
This 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
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Additional Powerpoints, and the full range of AS and A2 Chemistry topics,
are available from the KNOCKHARDY WEBSITE at...
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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.
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
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
Yellow
Cl2
Green
Br2
Red/brown
I2
Grey
GAS GAS LIQUID SOLID
Colour
State (at RTP)
APPEARANCEAPPEARANCE
Yellow Green Red/brown PurpleVapour colour

INCREASES down Group because more energy is required to separate
the larger molecules.
F2
Yellow
Cl2
Green
Br2
Red/brown
I2
Grey
GAS GAS LIQUID SOLID
Colour
State (at RTP)
APPEARANCEAPPEARANCE
BOILING POINTBOILING POINT
F2
- 188
Cl2
- 34
Br2
58
I2
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 2,8,18,18,7Configuration
9 17 35 53Atomic Number

GROUPGROUP SIMILARITIESSIMILARITIES
MOLECULAR FORMULAMOLECULAR FORMULA
F Cl Br I
Covalent Covalent Covalent CovalentBonding
F2 Cl2 Br2 I2Molecular formula
NOT TO SCALE
• all exist as diatomic molecules

ION FORMATIONION FORMATION
F Cl Br I
Configuration
Ion 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
Configuration
Ion 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 I
Reactivity 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 LESS
EASILY IT ATTRACTS THE ELECTRON IT NEEDS
TO FILL ITS OUTER SHELL’

THIS IS BECAUSE ‘THE LARGER THE HALOGEN ATOM, THE LESS
EASILY IT ATTRACTS THE ELECTRON IT NEEDS
TO FILL ITS OUTER SHELL’
THE HALIDES OF GROUP I ARE… WHITE IONIC SOLIDS
VERY 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 doesThe equation doesn’t balance - multiply the formulae until it does

2Na + Cl2 2NaCl
Na + Cl2 NaCl
Balanced equationBalanced equation

Cl
SODIUM ATOM
2,8,1
Na
CHLORINE ATOM
2,8,7
11 protons; 11 electrons 17 protons; 17 electrons
SODIUM CHLORIDE FORMATIONSODIUM CHLORIDE FORMATION

Cl
SODIUM ION
2,8
Na
CHLORIDE ION
2,8,8
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 ION
2,8
Na
CHLORIDE ION
2,8,8
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

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.

SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
BROMIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
CHLORINE
WATER
Pale green
BROMINE
WATER
Orange
A SOLUTION OF THE HALOGEN IS ADDED TO A SOLUTION OF A HALIDE
HALIDES ARE SALTS FORMED BETWEEN ELEMENTS AND HALOGENS

SODIUM
BROMIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
CHLORINE
WATER
Pale green
BROMINE
WATER
Orange
SODIUM
CHLORIDE
SOLUTION
Colourless
NO VISIBLE
REACTION
Experiment 1

SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
BROMINE
WATER
Orange
CHLORINE
WATER
Pale green
SODIUM
BROMIDE
SOLUTION
Colourless
BROMINE
produced
Experiment 2

SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
BROMIDE
SOLUTION
Colourless
BROMINE
WATER
Orange
CHLORINE
WATER
Pale green
SODIUM
IODIDE
SOLUTION
Colourless
IODINE
produced
Experiment 3

SODIUM
BROMIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
CHLORINE
WATER
Pale green
BROMINE
WATER
Orange
SODIUM
CHLORIDE
SOLUTION
Colourless
NO VISIBLE
REACTION
Experiment 4

SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
CHLORINE
WATER
Pale green
BROMINE
WATER
Orange
SODIUM
BROMIDE
SOLUTION
Colourless
NO VISIBLE
REACTION
Experiment 5

SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
BROMIDE
SOLUTION
Colourless
CHLORINE
WATER
Pale green
BROMINE
WATER
Orange
SODIUM
IODIDE
SOLUTION
Colourless
IODINE
produced
Experiment 6

SODIUM CHLORIDE
CHLORINE
SODIUM BROMIDE SODIUM IODIDE
Solution stays
colourless
NO REACTION
Solution goes from
colourless to orange-
yellow
NO REACTION
Solution goes from
yellow
BROMINE FORMED
Solution goes from
yellow
NO REACTION
Solution goes from
colourless to red
IODINE FORMED
BROMINE
Solution goes from
red
IODINE FORMED
SUMMARY 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
EQUATIONS

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

BROMIDE
EQUATIONS
Cl2(aq) + NaBr(aq) —> Br2(aq) + NaCl(aq)
The equation doesn’t balance - multiply the formulae until it doesThe equation doesn’t balance - multiply the formulae until it does

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

BROMIDE
EQUATIONS
Cl2(aq) + 2Br¯(aq) —> Br2(aq) + 2Cl¯(aq)
Cl2(aq) + 2NaBr(aq) —> Br2(aq) + 2NaCl(aq)
IONIC EQUATION

BROMIDE
EQUATIONS
Cl2(aq) + 2I¯(aq) —> I2(aq) + 2Cl¯(aq)
Cl2(aq) + 2NaI(aq) —> I2(aq) + 2NaCl(aq)
IONIC EQUATION

BROMIDE
EQUATIONS
Br2(aq) + 2I¯(aq) —> I2(aq) + 2Br¯(aq)
Br2(aq) + 2NaI(aq) —> I2(aq) + 2NaBr(aq)
IONIC EQUATION

BROMIDE
THIS SHOWS THAT A MORE REACTIVE HALOGEN WILL DISPLACE
A LESS REACTIVE ONE FROM AN AQUEOUS
SOLUTION OF ITS SALT
SUMMARY

BROMIDE
THIS SHOWS THAT A MORE REACTIVE HALOGEN WILL DISPLACE
A LESS REACTIVE ONE FROM AN AQUEOUS
SOLUTION 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)
EQUATIONS

PRESS THE SPACE BAR TO SEE WHAT HAPPENS
EXPLANATION
17+
CHLORINE ATOM
17 PROTONS
17 ELECTRONS
2,8,7
35+
BROMIDE ION
35 PROTONS
36 ELECTRONS
2,8,18,8
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.
EXPLANATION
CHLORINE ATOM
17 PROTONS
17 ELECTRONS
BROMIDE ION
35 PROTONS
36 ELECTRONS
CHLORIDE ION
17 PROTONS
18 ELECTRONS
BROMINE ATOM
35 PROTONS
35 ELECTRONS

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 ELEMENTS
3. 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.

GROUP VIIGROUP VII
The HalogensThe Halogens
THE ENDTHE END
© 2011© 2011 KNOCKHARDY PUBLISHING & JONATHAN HOPTONKNOCKHARDY PUBLISHING & JONATHAN HOPTON

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