GROUP VII
The Halogens
A guide for iGCSE students
2010
KNOCKHARDY PUBLISHING
SPECIFICATIONS
GROUP 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
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.
GROUP VII
CONTENTS
• Introduction
• Group trends
• Group similarities
• Reaction with metals
• Displacement reactions
• Summary
• Quick quiz
• Hydrogen chloride or hydrochloric acid?
INTRODUCTION
THE HALOGENS OCCUR IN GROUP VII OF THE PERIODIC TABLE
0
Group
1
2
3
4
5
6
7
F
Cl
Br
I
At
INTRODUCTION
THE HALOGENS OCCUR IN GROUP VII OF THE PERIODIC TABLE
0
Group
1
2
3
4
5
6
7
F
Cl
Br
I
At
THEY ARE NON-METALS AND HAVE ELECTRONIC CONFIGURATIONS
JUST ONE ELECTRON SHORT OF THE NEAREST NOBLE GAS
GROUP 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 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 TRENDS
GROUP TRENDS
APPEARANCE
F2
Cl2
Br2
I2
Colour
Yellow
Green
Red/brown
Grey
State (at RTP)
GAS
GAS
LIQUID
SOLID
Vapour colour
Yellow
Green
Red/brown
Purple
GROUP TRENDS
APPEARANCE
F2
Cl2
Br2
I2
Colour
Yellow
Green
Red/brown
Grey
State (at RTP)
GAS
GAS
LIQUID
SOLID
Vapour colour
Yellow
Green
Red/brown
Purple
BOILING POINT
Boiling point / °C
F2
Cl2
Br2
I2
- 188
- 34
58
183
INCREASES down Group because more energy is required to separate
the larger molecules.
GROUP TRENDS
ELECTRONIC CONFIGURATION
F
Cl
Br
I
Atomic Number
9
17
35
53
Configuration
2,7
2,8,7
2,8,18,7
2,8,18,18,7
• electrons go into shells further from the nucleus
GROUP TRENDS
ATOMIC & IONIC RADIUS
Atomic radius / nm
NOT TO SCALE
F
Cl
Br
I
0.064
0.099
0.111
0.128
GROUP TRENDS
ATOMIC & IONIC RADIUS
Atomic radius / nm
Ionic radius / nm
F
Cl
Br
I
0.064
0.099
0.111
0.128
F¯
Cl¯
Br¯
I¯
0.136
0.181
0.195
0.216
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
GROUP SIMILARITIES
GROUP SIMILARITIES
ELECTRONIC CONFIGURATION
F
Cl
Br
I
Atomic Number
9
17
35
53
Configuration
2,7
2,8,7
2,8,18,7
2,8,18,18,7
• 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
GROUP SIMILARITIES
MOLECULAR FORMULA
F
Cl
Br
I
Molecular formula
F2
Cl2
Br2
I2
Bonding
Covalent
Covalent
Covalent
Covalent
• all exist as diatomic molecules
NOT TO SCALE
GROUP SIMILARITIES
ION FORMATION
F
Cl
Br
I
Ion
F¯
Cl¯
Br¯
I¯
Configuration
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
GROUP SIMILARITIES
ION FORMATION
F
Cl
Br
I
Ion
F¯
Cl¯
Br¯
I¯
Configuration
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
REACTIVITY
F
Reactivity
Cl
Br
I
Increasingly reactive
• reactivity decreases down the Group / increases up the Group
REACTIONS OF HALOGENS
1. WITH METALS
2. WITH HALIDES
REACTION OF HALOGENS WITH METALS
REACTION OF HALOGENS WITH METALS
HALOGENS REACT WITH METALS TO PRODUCE METAL HALIDES.
REACTION OF HALOGENS WITH METALS
HALOGENS REACT WITH METALS TO PRODUCE METAL HALIDES.
THE EASE OF REACTION DECREASES DOWN THE GROUP F > Cl > Br > I
REACTION 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’
REACTION 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’
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 METALS
REACTION WITH ALKALI METALS - Equations
SODIUM
+ CHLORINE
SODIUM CHLORIDE
REACTION WITH ALKALI METALS - Equations
Na
SODIUM
+
Cl2
NaCl
CHLORINE
SODIUM CHLORIDE
REACTION WITH ALKALI METALS - Equations
Na
SODIUM
+
Cl2
NaCl
CHLORINE
SODIUM CHLORIDE
The equation doesn’t balance - multiply the formulae until it does
REACTION WITH ALKALI METALS - Equations
Na
+
SODIUM
2Na
+
Cl2
NaCl
CHLORINE
SODIUM CHLORIDE
Cl2
2NaCl
Balanced equation
SODIUM CHLORIDE FORMATION
Na
Cl
SODIUM ATOM
2,8,1
CHLORINE ATOM
2,8,7
11 protons; 11 electrons
17 protons; 17 electrons
SODIUM CHLORIDE FORMATION
Na+
Cl
SODIUM ION
2,8
CHLORIDE ION
2,8,8
11 protons; 10 electrons
17 protons; 18 electrons
both species now have ‘full’ outer shells; ie they
have the electronic configuration of a noble gas
SODIUM CHLORIDE FORMATION
Na+
Cl
SODIUM ION
2,8
CHLORIDE ION
2,8,8
Na
Na+
2,8,1
2,8
+
e¯
ELECTRON TRANSFERRED
Cl
2,8,7
+
e¯
Cl¯
2,8,8
DISPLACEMENT REACTIONS OF HALOGENS
DISPLACEMENT REACTIONS OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
DISPLACEMENT 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.
DISPLACEMENT 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.
THE REACTIONS ARE EXAMPLES OF REDOX REACTIONS
DISPLACEMENT REACTIONS OF HALOGENS
CHLORINE
WATER
Pale green
BROMINE
WATER
Orange
SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
BROMIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
A SOLUTION OF THE HALOGEN IS ADDED TO A SOLUTION OF A HALIDE
HALIDES ARE SALTS FORMED BETWEEN ELEMENTS AND HALOGENS
DISPLACEMENT REACTIONS OF HALOGENS
BROMINE
WATER
Orange
SODIUM
BROMIDE
SOLUTION
Colourless
Experiment 1
CHLORINE
WATER
Pale green
SODIUM
CHLORIDE
SOLUTION
Colourless
NO VISIBLE
REACTION
SODIUM
IODIDE
SOLUTION
Colourless
DISPLACEMENT REACTIONS OF HALOGENS
BROMINE
WATER
Orange
SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
Experiment 2
CHLORINE
WATER
Pale green
SODIUM
BROMIDE
SOLUTION
Colourless
BROMINE
produced
DISPLACEMENT REACTIONS OF HALOGENS
BROMINE
WATER
Orange
SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
BROMIDE
SOLUTION
Colourless
Experiment 3
CHLORINE
WATER
Pale green
SODIUM
IODIDE
SOLUTION
Colourless
IODINE
produced
DISPLACEMENT REACTIONS OF HALOGENS
CHLORINE
WATER
Pale green
SODIUM
BROMIDE
SOLUTION
Colourless
Experiment 4
BROMINE
WATER
Orange
SODIUM
CHLORIDE
SOLUTION
Colourless
NO VISIBLE
REACTION
SODIUM
IODIDE
SOLUTION
Colourless
DISPLACEMENT REACTIONS OF HALOGENS
CHLORINE
WATER
Pale green
SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
IODIDE
SOLUTION
Colourless
Experiment 5
BROMINE
WATER
Orange
SODIUM
BROMIDE
SOLUTION
Colourless
NO VISIBLE
REACTION
DISPLACEMENT REACTIONS OF HALOGENS
CHLORINE
WATER
Pale green
SODIUM
CHLORIDE
SOLUTION
Colourless
SODIUM
BROMIDE
SOLUTION
Colourless
Experiment 6
BROMINE
WATER
Orange
SODIUM
IODIDE
SOLUTION
Colourless
IODINE
produced
DISPLACEMENT REACTIONS OF HALOGENS
SUMMARY OF OBSERVATIONS
SODIUM CHLORIDE
1
SODIUM IODIDE
2
3
Solution goes from
colourless to orangeyellow
BROMINE FORMED
Solution goes from
colourless to orangered
IODINE FORMED
4
5
6
Solution goes from
colourless to orangeyellow
NO REACTION
Solution goes from
colourless to orangeyellow
NO REACTION
Solution stays
colourless
CHLORINE
NO REACTION
BROMINE
SODIUM BROMIDE
The colour change in Experiments 4 and 5 is
due to dilution – there is no reaction
Solution goes from
colourless to red
IODINE FORMED
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
CHLORINE + SODIUM BROMIDE
CHLORINE + SODIUM IODIDE
BROMINE + SODIUM IODIDE
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
CHLORINE + SODIUM BROMIDE
BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE
IODINE + SODIUM CHLORIDE
BROMINE + SODIUM IODIDE
IODINE + SODIUM BROMIDE
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
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
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
CHLORINE + SODIUM BROMIDE
BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE
IODINE + SODIUM CHLORIDE
BROMINE + SODIUM IODIDE
IODINE + SODIUM BROMIDE
Cl2(aq) +
NaBr(aq)
Cl2(aq) + 2NaBr(aq)
—> Br2(aq) +
NaCl(aq)
—> Br2(aq) + 2NaCl(aq)
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
CHLORINE + SODIUM BROMIDE
BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE
IODINE + SODIUM CHLORIDE
BROMINE + SODIUM IODIDE
IODINE + SODIUM BROMIDE
Cl2(aq) + 2NaBr(aq)
—> Br2(aq) + 2NaCl(aq)
IONIC EQUATION
Cl2(aq) + 2Br¯(aq) —>
Br2(aq) + 2Cl¯(aq)
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
CHLORINE + SODIUM BROMIDE
BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE
IODINE + SODIUM CHLORIDE
BROMINE + SODIUM IODIDE
IODINE + SODIUM BROMIDE
Cl2(aq) + 2NaI(aq)
—> I2(aq) + 2NaCl(aq)
IONIC EQUATION
Cl2(aq) + 2I¯(aq) —>
I2(aq) + 2Cl¯(aq)
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
CHLORINE + SODIUM BROMIDE
BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE
IODINE + SODIUM CHLORIDE
BROMINE + SODIUM IODIDE
IODINE + SODIUM BROMIDE
Br2(aq) + 2NaI(aq)
—> I2(aq) + 2NaBr(aq)
IONIC EQUATION
Br2(aq) + 2I¯(aq) —>
I2(aq) + 2Br¯(aq)
DISPLACEMENT REACTIONS OF HALOGENS
SUMMARY
CHLORINE + SODIUM BROMIDE
BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE
IODINE + SODIUM CHLORIDE
BROMINE + SODIUM IODIDE
IODINE + SODIUM BROMIDE
THIS SHOWS THAT
A MORE REACTIVE HALOGEN WILL DISPLACE
A LESS REACTIVE ONE FROM AN AQUEOUS
SOLUTION OF ITS SALT
DISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
CHLORINE + SODIUM BROMIDE
BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE
IODINE + SODIUM CHLORIDE
BROMINE + SODIUM IODIDE
IODINE + SODIUM 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)
DISPLACEMENT REACTIONS OF HALOGENS
EXPLANATION
17+
CHLORINE ATOM
17 PROTONS
17 ELECTRONS
2,8,7
35+
BROMIDE ION
35 PROTONS
36 ELECTRONS
2,8,18,8
THE CHLORINE
PRESS
ATOMTHE
PULLS
SPACE
AN ELECTRON
BAR TO SEEOUT
WHAT
OF HAPPENS
THE OUTER SHELL OF
THE BROMIDE ION – THE CHLORINE ATOM BECOMES A CHLORIDE ION AND
THE BROMIDE ION BECOMES A BROMINE ATOM.
DISPLACEMENT REACTIONS OF HALOGENS
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
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 HALOGENS - REDOX
DISPLACEMENT REACTIONS OF HALOGENS - REDOX
A REDOX REACTION INVOLVES BOTH OXIDATION AND REDUCTION
DISPLACEMENT REACTIONS OF HALOGENS - REDOX
A REDOX REACTION INVOLVES BOTH OXIDATION AND REDUCTION
REDUCTION IS THE…
GAIN OF ELECTRONS
OXIDATION IS THE…
REMOVAL OF ELECTRONS
DISPLACEMENT REACTIONS OF HALOGENS - REDOX
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)
DISPLACEMENT REACTIONS OF HALOGENS - REDOX
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.
THE BROMIDE IONS ARE OXIDISED…
CHLORINE IS THE
OXIDISING AGENT
ELECTRONS ARE REMOVED
ELECTRONS
REMOVED
Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)
OXIDISED
DISPLACEMENT REACTIONS OF HALOGENS - REDOX
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.
THE BROMIDE IONS ARE OXIDISED…
THE CHLORINE ATOMS ARE REDUCED…
ELECTRONS ARE REMOVED
ELECTRONS ARE GAINED
BROMIDE ION IS THE
REDUCING AGENT
Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)
REDUCED
GAIN OF ELECTRONS
DISPLACEMENT REACTIONS OF HALOGENS - REDOX
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.
THE BROMIDE IONS ARE OXIDISED…
THE CHLORINE ATOMS ARE REDUCED…
ELECTRONS ARE REMOVED
ELECTRONS ARE GAINED
ELECTRONS
REMOVED
Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)
REDUCED
OXIDISED
GAIN OF ELECTRONS
OXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
OXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F
Cl
Br
I
Atomic Number
9
17
35
53
Configuration
2,7
2,8,7
2,8,18,7
2,8,18,18,7
Atomic radius / nm
0.064
0.099
0.111
0.128
---- DECREASING OXIDISING POWER ----->
OXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F
Cl
Br
I
Atomic Number
9
17
35
53
Configuration
2,7
2,8,7
2,8,18,7
2,8,18,18,7
Atomic radius / nm
0.064
0.099
0.111
0.128
---- DECREASING OXIDISING POWER ----->
THE SMALLER THE HALOGEN, THE LESS SHIELDING THERE IS AND THE
GREATER THE EFFECTIVE PULL OF THE NUCLEUS.
OXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F
Cl
Br
I
Atomic Number
9
17
35
53
Configuration
2,7
2,8,7
2,8,18,7
2,8,18,18,7
Atomic radius / nm
0.064
0.099
0.111
0.128
---- DECREASING OXIDISING POWER ----->
THE SMALLER THE HALOGEN, THE LESS SHIELDING THERE IS AND THE
GREATER THE EFFECTIVE PULL OF THE NUCLEUS.
THE GREATER THE PULL OF THE NUCLEUS, THE EASIER THE ATOM CAN
PULL AN ELECTRON OUT OF ANOTHER SPECIES.
OXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F
Cl
Br
I
Atomic Number
9
17
35
53
Configuration
2,7
2,8,7
2,8,18,7
2,8,18,18,7
Atomic radius / nm
0.064
0.099
0.111
0.128
---- DECREASING OXIDISING POWER ----->
THE SMALLER THE HALOGEN, THE LESS SHIELDING THERE IS AND THE
GREATER THE EFFECTIVE PULL OF THE NUCLEUS.
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.
GROUP VII - SUMMARY
FLUORINE
CHLORINE
BROMINE
IODINE
SYMBOL
F
Cl
Br
I
MOLECULAR
FORMULA
F2
Cl2
Br2
I2
APPEARANCE
PALE YELLOW
PALE GREEN
RED-BROWN
GREY-BLACK
STATE (room temp)
GAS
GAS
LIQUID
SOLID
COLOUR OF VAPOUR
PALE YELLOW
GREEN
RED-BROWN
PURPLE
ELECTRONIC
CONFIGURATION
2,7
2,8,7
2,8,18,7
2,8,18,18,7
INCREASES
BOILING POINT
ION
(electronic config)
F¯
Cl¯
Br¯
I¯
2,8
2,8,8
2,8,18,8
2,8,18,18,8
REACTION WITH
SODIUM
PRODUCT OF REACTION
WITH SODIUM
LESS REACTIVE
SODIUM
FLUORIDE (NaF)
SODIUM
CHLORIDE (NaCl)
SODIUM
BROMIDE (NaBr)
SODIUM IODIDE
(NaI)
QUICK 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 - 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.
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.
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 OR HYDROCHLORIC ACID?
HYDROGEN CHLORIDE
colourless gas
covalent molecule
HCl(g)
poor
no reaction
HCl(g)
HYDROCHLORIC ACID
Appearance
Bonding
Formula
Conductivity
Dry blue litmus
—> H+ (aq)
colourless soln.
aqueous ions
HCl(aq)
good
goes red
+ Cl¯(aq)
DOES HYDROGEN CHLORIDE ALWAYS DISSOCIATE?
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.
WATER
A polar solvent
Molecules dissociate
The solution turns litmus
paper red because of the
H+(aq) ions.
METHYLBENZENE
A non-polar solvent
NO dissociation
The solution does not
litmus paper red because
there are NO H+(aq) ions.
WHY DOES HYDROGEN CHLORIDE DISSOCIATE IN WATER?
WATER IS A POLAR SOLVENT –
it has one end which is slightly positive
and another end which is slightly positive.
negative
end
positive
end
WHY DOES HYDROGEN CHLORIDE DISSOCIATE IN WATER?
WATER IS A POLAR SOLVENT –
it has one end which is slightly positive
and another end which is slightly positive.
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.
HCl(g)
—> H+ (aq)
+ Cl¯(aq)
negative
end
positive
end
WHY DOES HYDROGEN CHLORIDE DISSOCIATE IN WATER?
WATER IS A POLAR SOLVENT –
it has one end which is slightly positive
and another end which is slightly positive.
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.
HCl(g)
—> H+ (aq)
+ Cl¯(aq)
The chloride ions are attracted to the
slightly positive hydrogen end of water.
The slightly negative oxygen end of
water attracts the H+ ions.
negative
end
positive
end
GROUP VII
The Halogens
THE END
© 2011 KNOCKHARDY PUBLISHING & JONATHAN HOPTON