GROUP VII GROUP VII The Halogens The Halogens A guide for A guide for i i GCSE students GCSE students KNOCKHARDY PUBLISHING KNOCKHARDY PUBLISHING 2010 2010 SPECIFICATIONS SPECIFICATIONS
GROUP VIIGROUP VIIThe HalogensThe Halogens
A guide for A guide for iiGCSE studentsGCSE students
KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING2010 2010
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 board.
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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
• 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
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
GROUP TRENDSGROUP TRENDS
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
GROUP TRENDSGROUP TRENDS
• 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
GROUP TRENDSGROUP TRENDS
F Cl Br I
ATOMIC & IONIC RADIUSATOMIC & IONIC RADIUS
0.064 0.099 0.111 0.128Atomic radius / nm
NOT TO SCALE
GROUP TRENDSGROUP TRENDS
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
GROUP GROUP 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
GROUP GROUP SIMILARITIESSIMILARITIES
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
GROUP GROUP SIMILARITIESSIMILARITIES
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
REACTION OF HALOGENS WITH METALSREACTION OF HALOGENS WITH METALS
HALOGENS REACT WITH METALS TO PRODUCE METAL 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
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’
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’
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+
REACTION WITH ALKALI METALS - EquationsREACTION WITH ALKALI METALS - Equations
Na + Cl2 NaCl
SODIUM CHLORINE SODIUM CHLORIDE
REACTION WITH ALKALI METALS - EquationsREACTION WITH ALKALI METALS - Equations
Na + Cl2 NaCl
SODIUM CHLORINE SODIUM CHLORIDE
The equation doesn’t balance - multiply the formulae until it doesThe equation doesn’t balance - multiply the formulae until it does
REACTION WITH ALKALI METALS - EquationsREACTION WITH ALKALI METALS - Equations
2Na + Cl2 2NaCl
Na + Cl2 NaCl
SODIUM CHLORINE SODIUM CHLORIDE
Balanced equationBalanced 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
SODIUM CHLORIDE FORMATIONSODIUM CHLORIDE FORMATION
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
+
SODIUM CHLORIDE FORMATIONSODIUM CHLORIDE FORMATION
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
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.
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.
THE REACTIONS ARE EXAMPLES OF REDOX REACTIONS
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
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
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
SODIUMBROMIDESOLUTIONColourless
SODIUMIODIDE
SOLUTIONColourless
CHLORINEWATER
Pale green
BROMINEWATEROrange
SODIUMCHLORIDESOLUTIONColourless
NO VISIBLE REACTION
Experiment 1
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
SODIUMCHLORIDESOLUTIONColourless
SODIUMIODIDE
SOLUTIONColourless
BROMINEWATEROrange
CHLORINEWATER
Pale green
SODIUMBROMIDESOLUTIONColourless
BROMINE produced
Experiment 2
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
SODIUMCHLORIDESOLUTIONColourless
SODIUMBROMIDESOLUTIONColourless
BROMINEWATEROrange
CHLORINEWATER
Pale green
SODIUMIODIDE
SOLUTIONColourless
IODINE produced
Experiment 3
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
SODIUMBROMIDESOLUTIONColourless
SODIUMIODIDE
SOLUTIONColourless
CHLORINEWATER
Pale green
BROMINEWATEROrange
SODIUMCHLORIDESOLUTIONColourless
NO VISIBLE REACTION
Experiment 4
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
SODIUMCHLORIDESOLUTIONColourless
SODIUMIODIDE
SOLUTIONColourless
CHLORINEWATER
Pale green
BROMINEWATEROrange
SODIUMBROMIDESOLUTIONColourless
NO VISIBLE REACTION
Experiment 5
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
SODIUMCHLORIDESOLUTIONColourless
SODIUMBROMIDESOLUTIONColourless
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-
yellow
NO REACTION
Solution goes from colourless to orange-
yellow
BROMINE FORMED
Solution goes from colourless to orange-
yellow
NO REACTION
Solution goes from colourless to red
IODINE FORMED
BROMINE
Solution goes from colourless to orange-
red
IODINE FORMED
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
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
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT 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 HALOGENSDISPLACEMENT 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 HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
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
CHLORINE + SODIUM BROMIDE BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE IODINE + SODIUM CHLORIDE BROMINE + SODIUM IODIDE IODINE + SODIUM BROMIDE
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
Cl2(aq) + 2NaBr(aq) —> Br2(aq) + 2NaCl(aq)
Cl2(aq) + NaBr(aq) —> Br2(aq) + NaCl(aq)
CHLORINE + SODIUM BROMIDE BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE IODINE + SODIUM CHLORIDE BROMINE + SODIUM IODIDE IODINE + SODIUM BROMIDE
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
Cl2(aq) + 2Br¯(aq) —> Br2(aq) + 2Cl¯(aq)
Cl2(aq) + 2NaBr(aq) —> Br2(aq) + 2NaCl(aq)
IONIC EQUATION
CHLORINE + SODIUM BROMIDE BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE IODINE + SODIUM CHLORIDE BROMINE + SODIUM IODIDE IODINE + SODIUM BROMIDE
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
Cl2(aq) + 2I¯(aq) —> I2(aq) + 2Cl¯(aq)
Cl2(aq) + 2NaI(aq) —> I2(aq) + 2NaCl(aq)
IONIC EQUATION
CHLORINE + SODIUM BROMIDE BROMINE + SODIUM CHLORIDE
CHLORINE + SODIUM IODIDE IODINE + SODIUM CHLORIDE BROMINE + SODIUM IODIDE IODINE + SODIUM BROMIDE
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
Br2(aq) + 2I¯(aq) —> I2(aq) + 2Br¯(aq)
Br2(aq) + 2NaI(aq) —> I2(aq) + 2NaBr(aq)
IONIC EQUATION
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 DISPLACEA LESS REACTIVE ONE FROM AN AQUEOUSSOLUTION OF ITS SALT
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT 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 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)
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
EQUATIONS
PRESS THE SPACE BAR TO SEE WHAT HAPPENS
DISPLACEMENT REACTIONS OF HALOGENSDISPLACEMENT REACTIONS OF HALOGENS
EXPLANATION
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 HALOGENS
EXPLANATION
CHLORINE ATOM17 PROTONS
17 ELECTRONS
BROMIDE ION35 PROTONS
36 ELECTRONS
CHLORIDE 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
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
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.
DISPLACEMENT REACTIONS OF HALOGENS - DISPLACEMENT REACTIONS OF HALOGENS - REDOXREDOX
Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)
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… ELECTRONS ARE REMOVED
DISPLACEMENT REACTIONS OF HALOGENS - DISPLACEMENT REACTIONS OF HALOGENS - REDOXREDOX
Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)
OXIDISED
ELECTRONSREMOVED
CHLORINE IS THE OXIDISING AGENTCHLORINE IS THE OXIDISING AGENT
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… ELECTRONS ARE REMOVED
THE CHLORINE ATOMS ARE REDUCED… ELECTRONS ARE GAINED
DISPLACEMENT REACTIONS OF HALOGENS - DISPLACEMENT REACTIONS OF HALOGENS - REDOXREDOX
Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)
REDUCED
GAIN OF ELECTRONS
BROMIDE ION IS THE REDUCING AGENT
BROMIDE ION IS THE REDUCING AGENT
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… ELECTRONS ARE REMOVED
THE CHLORINE ATOMS ARE REDUCED… ELECTRONS ARE GAINED
DISPLACEMENT REACTIONS OF HALOGENS - DISPLACEMENT REACTIONS OF HALOGENS - REDOXREDOX
Cl2(aq) + 2Br¯(aq) ——> Br2(aq) + 2Cl¯(aq)
REDUCED OXIDISED
ELECTRONSREMOVED
GAIN OF ELECTRONS
OXIDISING POWER OF HALOGENSOXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
OXIDISING POWER OF HALOGENSOXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F Cl Br I
2,7 2,8,7 2,8,18,7 2,8,18,18,7Configuration
9 17 35 53Atomic Number
0.064 0.099 0.111 0.128Atomic radius / nm
---- DECREASING OXIDISING POWER ----->
OXIDISING POWER OF HALOGENSOXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F Cl Br I
2,7 2,8,7 2,8,18,7 2,8,18,18,7Configuration
9 17 35 53Atomic Number
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.
---- DECREASING OXIDISING POWER ----->
OXIDISING POWER OF HALOGENSOXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F Cl Br I
2,7 2,8,7 2,8,18,7 2,8,18,18,7Configuration
9 17 35 53Atomic Number
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.
THE GREATER THE PULL OF THE NUCLEUS, THE EASIER THE ATOM CAN PULL AN ELECTRON OUT OF ANOTHER SPECIES.
---- DECREASING OXIDISING POWER ----->
OXIDISING POWER OF HALOGENSOXIDISING POWER OF HALOGENS
HALOGENS GET LESS REACTIVE AS THE GROUP IS DESCENDED
THIS IS DUE TO THEIR DECREASING OXIDISING ABILITY
F Cl Br I
2,7 2,8,7 2,8,18,7 2,8,18,18,7Configuration
9 17 35 53Atomic Number
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.
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.
---- DECREASING OXIDISING POWER ----->
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.
HYDROGEN CHLORIDE OR HYDROCHLORIC ACID? HYDROGEN CHLORIDE OR HYDROCHLORIC ACID?
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 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 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 OR HYDROCHLORIC ACID?
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
HYDROGEN CHLORIDE OR HYDROCHLORIC ACID? HYDROGEN CHLORIDE OR HYDROCHLORIC ACID?
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.
WATER
A polar solvent
Molecules dissociate
The solution turns litmus paper red because of the H+(aq) ions.
DOES HYDROGEN CHLORIDE ALWAYS DISSOCIATE?DOES HYDROGEN CHLORIDE ALWAYS DISSOCIATE?
METHYLBENZENE
A non-polar solvent
NO dissociation
The 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
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?
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
HCl(g) —> H+ (aq) + Cl¯(aq)
WHY DOES HYDROGEN CHLORIDE DISSOCIATE IN WATER?WHY DOES HYDROGEN CHLORIDE DISSOCIATE IN WATER?
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.
HCl(g) —> H+ (aq) + Cl¯(aq)
WATER IS A POLAR SOLVENT – it has one end which is slightly positive and another end which is slightly positive.
positive end
negative end
GROUP VIIGROUP VIIThe HalogensThe Halogens
THE ENDTHE END
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