2. STRUCTURE & BONDING
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.
Accompanying notes on this, 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.
3. STRUCTURE & BONDING
OVERVIEW
The following slides illustrate how the type of chemical
bonding affects the physical properties of elements and
compounds.
To understand how the three main chemical bonds types are
formed, view the powerpoint ‘CHEMICAL BONDING’ available
from the KNOCKHARDY SCIENCE GCSE WEBSITE at...
www.knockhardy.org.uk/gcse.htm
6. IONIC BONDING
IONIC BONDING RESULTS FROM THE ELECTROSTATIC ATTRACTION
BETWEEN IONS OF OPPOSITE CHARGE.
IONS ARE FORMED WHEN SPECIES GAIN ELECTRONS TO FORM
NEGATIVE IONS (ANIONS)
7. IONIC BONDING
IONIC BONDING RESULTS FROM THE ELECTROSTATIC ATTRACTION
BETWEEN IONS OF OPPOSITE CHARGE.
IONS ARE FORMED WHEN SPECIES GAIN ELECTRONS TO FORM
NEGATIVE IONS (ANIONS)
or ‘LOSE’ ELECTRONS TO FORM
POSITIVE IONS (CATIONS)
8. IONIC BONDING
IONIC BONDING RESULTS FROM THE ELECTROSTATIC ATTRACTION
BETWEEN IONS OF OPPOSITE CHARGE.
IONS ARE FORMED WHEN SPECIES GAIN ELECTRONS TO FORM
NEGATIVE IONS (ANIONS)
or ‘LOSE’ ELECTRONS TO FORM
POSITIVE IONS (CATIONS)
NOTE: THE ELECTRONS ARE NOT REALLY ‘LOST’ BUT MOVE AWAY
9. IONIC BONDING
IONIC BONDING RESULTS FROM THE ELECTROSTATIC ATTRACTION
BETWEEN IONS OF OPPOSITE CHARGE.
IONS ARE FORMED WHEN SPECIES GAIN ELECTRONS TO FORM
NEGATIVE IONS (ANIONS)
or ‘LOSE’ ELECTRONS TO FORM
POSITIVE IONS (CATIONS)
NOTE: THE ELECTRONS ARE NOT REALLY ‘LOST’ BUT MOVE AWAY
WHEN METALS IN GROUPS I and II REACT WITH NON-METALS IN
GROUPS VI and VII, IONIC COMPOUNDS ARE FORMED; SODIUM
CHLORIDE IS THE BEST KNOWN EXAMPLE.
10. FORMATION OF SODIUM CHLORIDE
Cl
SODIUM ATOM
2,8,1
Na
CHLORINE ATOM
2,8,7
PRESS THE SPACE BAR TO START / ADVANCE AN ANIMATION
13. IONIC BONDING IN SODIUM CHLORIDE
Cl- chloride ion
Na+ sodium ion
14. IONIC BONDING IN SODIUM CHLORIDE
Cl- chloride ion
Na+ sodium ion
SODIUM CHLORIDE HAS A REGULAR STRUCTURE - A GIANT IONIC LATTICE
15. IONIC BONDING IN SODIUM CHLORIDE
Cl- chloride ion
Na+ sodium ion
SODIUM CHLORIDE HAS A REGULAR STRUCTURE - A GIANT IONIC LATTICE
OPPOSITELY CHARGED IONS ARE HELD TOGETHER BY STRONG
ELECTROSTATIC FORCES ACTING IN ALL DIRECTIONS
16. IONIC BONDING IN SODIUM CHLORIDE
Cl- chloride ion
Na+ sodium ion
SODIUM CHLORIDE HAS A REGULAR STRUCTURE - A GIANT IONIC LATTICE
OPPOSITELY CHARGED IONS ARE HELD TOGETHER BY STRONG
ELECTROSTATIC FORCES ACTING IN ALL DIRECTIONS
THERE IS NO SINGLE NaCl , JUST (EQUAL) VAST NUMBERS OF IONS
17. IONIC BONDING IN SODIUM CHLORIDE
Cl- chloride ion
Na+ sodium ion
SODIUM CHLORIDE HAS A REGULAR STRUCTURE - A GIANT IONIC LATTICE
OPPOSITELY CHARGED IONS ARE HELD TOGETHER BY STRONG
ELECTROSTATIC FORCES ACTING IN ALL DIRECTIONS
THERE IS NO SINGLE NaCl , JUST (EQUAL) VAST NUMBERS OF IONS
YOU DO NOT GET MOLECULES OF SODIUM CHLORIDE
18. EACH SODIUM ION IS SURROUNDED BY SIX CHLORIDE IONS
EACH CHLORIDE ION IS SURROUNDED BY SIX SODIUM IONS
Cl- Chloride ion Na+ Sodium ion
IONIC BONDING IN SODIUM CHLORIDE
19. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
VERY HIGH MELTING POINTS
Na+
Cl- Na+
Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl- Na+
Cl-
IONS ARE HELD IN THE
LATTICE BY THE STRONG
ELECTROSTATIC FORCES
A LOT OF ENERGY IS NEEDED
TO SEPARATE THE IONS
20. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
VERY HIGH MELTING POINTS
Na+
Cl- Na+
Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl- Na+
Cl-
IONS ARE HELD IN THE
LATTICE BY THE STRONG
ELECTROSTATIC FORCES
A LOT OF ENERGY IS NEEDED
TO SEPARATE THE IONS
Na+ Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl-
THE IONS HAVE MORE
FREEDOM AND THE SODIUM
CHLORIDE BECOMES LIQUID
21. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
SOLUBILITY IN WATER
IONIC COMPOUNDS ARE USUALLY SOLUBLE IN WATER
22. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
SOLUBILITY IN WATER
Na+
Cl- Na+
Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl- Na+
Cl-
IONIC COMPOUNDS ARE USUALLY SOLUBLE IN WATER
Na+
Cl-
WATER IS A ‘POLAR’ SOLVENT. THE HYDROGEN END IS SLIGHTLY
POSITIVE AND THE OXYGEN END SLIGHTLY NEGATIVE.
O
H
H
O
H
H
O
H
H
O
H
H
O
H
H
23. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
SOLUBILITY IN WATER
Na+
Cl- Na+
Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl- Na+
Cl-
IONIC COMPOUNDS ARE USUALLY SOLUBLE IN WATER
Na+
Cl-
WATER IS A ‘POLAR’ SOLVENT. THE HYDROGEN END IS SLIGHTLY
POSITIVE AND THE OXYGEN END SLIGHTLY NEGATIVE.
ALTHOUGH IT REQUIRES A LOT OF ENERGY TO SEPARATE THE
IONS, THIS IS MORE THAN COMPENSATED FOR BY THE
STABILISING EFFECT OF THE WATER SURROUNDING EACH ION
O
H
H
O
H
H
O
H
H
O
H
H
O
H
H
24. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
ELECTRICAL PROPERTIES
Na+
Cl- Na+
Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl- Na+
Cl-
WHEN SOLID, THE IONS
ARE NOT FREE TO MOVE
NO CONDUCTION
OF ELECTRICITY
SOLID
SOLID IONIC COMPOUNDS DO NOT CONDUCT ELECTRICITY
25. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
ELECTRICAL PROPERTIES
Na+
Cl- Na+
Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl- Na+
Cl-
WHEN SOLID, THE IONS
ARE NOT FREE TO MOVE
NO CONDUCTION
OF ELECTRICITY
Na+ Cl-
Na+
Cl-
Na+
Cl-
Na+
Cl-
SOLID MOLTEN
WHEN MOLTEN, THE IONS
ARE FREE TO MOVE
ELECTRICITY IS
CONDUCTED
MOLTEN IONIC COMPOUNDS DO CONDUCT ELECTRICITY
27. PHYSICAL PROPERTIES OF IONIC COMPOUNDS
IONIC SOLIDS ARE BRITTLE
IF YOU HIT A CRYSTAL OF SODIUM CHLORIDE WITH A HAMMER,
THE CRYSTAL BREAKS INTO PIECES.
28. + +
+ +
+ +
+ +
- -
- -
- -
- -
+ +
+ +
IF YOU MOVE A LAYER OF IONS, IONS OF THE SAME CHARGE END UP
NEXT TO EACH OTHER.
THE LAYERS REPEL EACH OTHER AND THE CRYSTAL BREAKS UP.
PHYSICAL PROPERTIES OF IONIC COMPOUNDS
IONIC SOLIDS ARE BRITTLE
IF YOU HIT A CRYSTAL OF SODIUM CHLORIDE WITH A HAMMER,
THE CRYSTAL BREAKS INTO PIECES.
30. METALLIC BONDING
METALS CONSIST OF GIANT STRUCTURES OF REPEATING IONS
ARRANGED IN A REGULAR CRYSTAL LATTICE AND HELD
TOGETHER BY A MOBILE ‘CLOUD’ OR ‘SEA’ OF ELECTRONS.
Atoms arranged
in a regular lattice
31. METALLIC BONDING
METALS CONSIST OF GIANT STRUCTURES OF REPEATING IONS
ARRANGED IN A REGULAR CRYSTAL LATTICE AND HELD
TOGETHER BY A MOBILE ‘CLOUD’ OR ‘SEA’ OF ELECTRONS.
Atoms arranged
in a regular lattice
The outer shell electrons of
each atom leave to join a
mobile ‘cloud’ of electrons
which holds the positive
ions together.
32. METALLIC BONDING
METALS CONSIST OF GIANT STRUCTURES OF REPEATING IONS
ARRANGED IN A REGULAR CRYSTAL LATTICE AND HELD
TOGETHER BY A MOBILE ‘CLOUD’ OR ‘SEA’ OF ELECTRONS.
Atoms arranged
in a regular lattice
The outer shell electrons of
each atom leave to join a
mobile ‘cloud’ of electrons
which holds the positive
ions together.
THE ELECTRONS ARE SAID
TO BE ‘DELOCALISED’
(not confined to any one place)
33. PHYSICAL PROPERTIES OF METALS
VERY GOOD CONDUCTORS OF ELECTRICITY
For a substance to conduct electricity
it must have mobile ions or electrons.
34. PHYSICAL PROPERTIES OF METALS
VERY GOOD CONDUCTORS OF ELECTRICITY
For a substance to conduct electricity
it must have mobile ions or electrons.
ELECTRONS CAN MOVE THROUGH
35. PHYSICAL PROPERTIES OF METALS
VERY GOOD CONDUCTORS OF ELECTRICITY
THE MOBILE ELECTRON CLOUD IN METALS
PERMITS THE CONDUCTION OF ELECTRICITY
For a substance to conduct electricity
it must have mobile ions or electrons.
ELECTRONS CAN MOVE THROUGH
36. PHYSICAL PROPERTIES OF METALS
VERY GOOD CONDUCTORS OF HEAT
THE MOBILE ELECTRON CLOUD IN METALS
PERMITS THE CONDUCTION OF HEAT
For a substance to conduct heat
it must have mobile electrons.
ELECTRONS CAN MOVE
37. PHYSICAL PROPERTIES OF METALS
CAN BE BENT AND SHAPED
Metals can have their shapes changed relatively easily
38. MALLEABLE CAN BE HAMMERED INTO SHEETS
DUCTILE CAN BE DRAWN INTO RODS AND WIRES
PHYSICAL PROPERTIES OF METALS
CAN BE BENT AND SHAPED
Metals can have their shapes changed relatively easily
39. MALLEABLE CAN BE HAMMERED INTO SHEETS
DUCTILE CAN BE DRAWN INTO RODS AND WIRES
As the metal is beaten into another shape the mobile electrons
in the cloud continue to hold the positive ions together.
Some metals, such as gold, can be hammered
into sheets thin enough to be translucent.
PHYSICAL PROPERTIES OF METALS
CAN BE BENT AND SHAPED
Metals can have their shapes changed relatively easily
40. PHYSICAL PROPERTIES OF METALS
ALLOYS
Alloys are usually made from two or more different metals.
41. Why use To improve the properties of metals;
alloys? it usually makes them stronger
PHYSICAL PROPERTIES OF METALS
ALLOYS
Alloys are usually made from two or more different metals.
42. Why use To improve the properties of metals;
alloys? it usually makes them stronger
How do The different sized atoms of the metals distort
they work? the layers in the structure , making it more
difficult for them to slide over each other and so
make alloys harder than pure metals.
PHYSICAL PROPERTIES OF METALS
ALLOYS
Alloys are usually made from two or more different metals.
43. Steel an alloy of IRON and CARBON (a non-metal!)
- low-carbon steels are easily shaped
- high-carbon steels are hard
PHYSICAL PROPERTIES OF METALS
ALLOYS - Examples
Alloys are usually made from two or more different metals.
44. Steel an alloy of IRON and CARBON (a non-metal!)
- low-carbon steels are easily shaped
- high-carbon steels are hard
- some steels contain other metals
chromium / nickel stainless steel
manganese very hard for railway points
tungsten very hard for drill tips
PHYSICAL PROPERTIES OF METALS
ALLOYS - Examples
Alloys are usually made from two or more different metals.
45. Steel an alloy of IRON and CARBON (a non-metal!)
- low-carbon steels are easily shaped
- high-carbon steels are hard
- some steels contain other metals
chromium / nickel stainless steel
manganese very hard for railway points
tungsten very hard for drill tips
Copper Pure copper, like gold and aluminium, is too soft
for many uses. It is mixed with similar metals.
Brass copper / zinc
Bronze copper / tin
Coinage metal copper /nickel
PHYSICAL PROPERTIES OF METALS
ALLOYS - Examples
Alloys are usually made from two or more different metals.
46. PHYSICAL PROPERTIES OF METALS
SHAPE MEMORY ALLOYS
Shape memory alloys can return to their original shape after being deformed
47. Shape memory alloy (SMA) can be deformed, and then returned
to their original shape by the application of heat.
PHYSICAL PROPERTIES OF METALS
SHAPE MEMORY ALLOYS
Shape memory alloys can return to their original shape after being deformed
48. Shape memory alloy (SMA) can be deformed, and then returned
to their original shape by the application of heat.
They are made of a NICKLEL-TITANIUM alloy - ‘NITINOL’
Small amounts of other metals can be added to alter properties
PHYSICAL PROPERTIES OF METALS
SHAPE MEMORY ALLOYS
Shape memory alloys can return to their original shape after being deformed
49. Shape memory alloy (SMA) can be deformed, and then returned
to their original shape by the application of heat.
They are made of a NICKLEL-TITANIUM alloy - ‘NITINOL’
Small amounts of other metals can be added to alter properties
Examples Key-hole surgery instruments
Spectacle frames
Thermostats
Dental braces
PHYSICAL PROPERTIES OF METALS
SHAPE MEMORY ALLOYS
Shape memory alloys can return to their original shape after being deformed
51. COVALENT BONDING
A covalent bond consists of…
a shared pair of electrons with one electron being
supplied by each atom either side of the bond.
COVALENT BONDS ARE STRONG
52. COVALENT BONDING
A covalent bond consists of…
a shared pair of electrons with one electron being
supplied by each atom either side of the bond.
COVALENT BONDS ARE STRONG
Covalent bond are found between the atoms in molecules.
Molecules can be SIMPLE MOLECULES H2, CO2, CH4
or GIANT MOLECULES diamond, graphite, silica
53. SIMPLE COVALENT MOLECULES
Covalent bonding between the atoms in each molecule is STRONG
Bonding between individual molecules is not covalent and is WEAK
STRONG
COVALENT
BONDS
(hard to break)
VERY WEAK ATTRACTION
BETWEEN MOLECULES
(easy to break)
Because the attractions
between molecules are very
weak, simple covalent
molecules usually have low
melting and boiling points
because it is easy to
separate the molecules
54. SIMPLE COVALENT MOLECULES
GENERAL PROPERTIES OF SIMPLE MOLECULES
APPEARANCE gases, liquids or solids with low melting and boiling points
MELTING POINT Very low
Weak attractive forces between molecules means that very
little energy is needed to move them apart
ELECTRICAL Don’t conduct electricity - have no mobile ions or electrons
Covalent bonding between the atoms in each molecule is STRONG
Bonding between individual molecules is not covalent and is WEAK
55. GIANT COVALENT MOLECULES
In giant covalent molecules there are many atoms joined together in a
regular arrangement by a very large number of covalent bonds.
56. GIANT COVALENT MOLECULES
In giant covalent molecules there are many atoms joined together in a
regular arrangement by a very large number of covalent bonds.
GENERAL PROPERTIES OF GIANT MOLECULES
MELTING POINT Very high
structure is made up of a large number of covalent bonds,
all of which need to be broken if atoms are to be separated
57. GIANT COVALENT MOLECULES
In giant covalent molecules there are many atoms joined together in a
regular arrangement by a very large number of covalent bonds.
GENERAL PROPERTIES OF GIANT MOLECULES
MELTING POINT Very high
structure is made up of a large number of covalent bonds,
all of which need to be broken if atoms are to be separated
ELECTRICAL Don’t conduct electricity - have no mobile ions or electrons
BUT... Graphite conducts electricity
GIANT MOLECULES = MACROMOLECULES = COVALENT NETWORKS
They all mean the same!
58. GIANT COVALENT MOLECULES
In giant covalent molecules there are many atoms joined together in a
regular arrangement by a very large number of covalent bonds.
GENERAL PROPERTIES OF GIANT MOLECULES
MELTING POINT Very high
structure is made up of a large number of covalent bonds,
all of which need to be broken if atoms are to be separated
ELECTRICAL Don’t conduct electricity - have no mobile ions or electrons
BUT... Graphite conducts electricity
STRENGTH Hard - exist in a rigid tetrahedral structure
Diamond and silica (SiO2)... but
Graphite is soft
59. GIANT COVALENT MOLECULES
In giant covalent molecules there are many atoms joined together in a
regular arrangement by a very large number of covalent bonds.
GENERAL PROPERTIES OF GIANT MOLECULES
MELTING POINT Very high
structure is made up of a large number of covalent bonds,
all of which need to be broken if atoms are to be separated
ELECTRICAL Don’t conduct electricity - have no mobile ions or electrons
BUT... Graphite conducts electricity
STRENGTH Hard - exist in a rigid tetrahedral structure
Diamond and silica (SiO2)... but
Graphite is soft
GIANT MOLECULES = MACROMOLECULES = COVALENT NETWORKS
They all mean the same!
61. GIANT COVALENT MOLECULES
DIAMOND
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
STRENGTH STRONG
each carbon atom is joined to four others in a rigid structure
Coordination Number = 4
62. GIANT COVALENT MOLECULES
DIAMOND
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
STRENGTH STRONG
each carbon atom is joined to four others in a rigid structure
Coordination Number = 4
ELECTRICAL NON-CONDUCTOR
No free electrons - all 4 carbon electrons used for bonding
63. GIANT COVALENT MOLECULES
DIAMOND
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
STRENGTH STRONG
each carbon atom is joined to four others in a rigid structure
Coordination Number = 4
ELECTRICAL NON-CONDUCTOR
No free electrons - all 4 carbon electrons used for bonding
64. GIANT COVALENT MOLECULES
GRAPHITE
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
layers can slide over each other -
used as a lubricant and in pencils
65. GIANT COVALENT MOLECULES
GRAPHITE
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
STRENGTH SOFT
each carbon is joined to three others in a layered structure
Coordination Number = 3
layers are held by weak intermolecular forces
layers can slide over each other -
used as a lubricant and in pencils
66. GIANT COVALENT MOLECULES
GRAPHITE
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
STRENGTH SOFT
each carbon is joined to three others in a layered structure
Coordination Number = 3
layers are held by weak intermolecular forces
can slide over each other
ELECTRICAL CONDUCTOR
Only three carbon electrons are used for bonding which
leaves the fourth to move freely along layers
layers can slide over each other -
used as a lubricant and in pencils
67. GIANT COVALENT MOLECULES
GRAPHITE
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
STRENGTH SOFT
each carbon is joined to three others in a layered structure
Coordination Number = 3
layers are held by weak intermolecular forces
can slide over each other
ELECTRICAL CONDUCTOR
Only three carbon electrons are used for bonding which
leaves the fourth to move freely along layers
layers can slide over each other-
used as a lubricant and in pencils
68. ANOTHER FORM OF CARBON
FULLERENES
Although not officially classed as giant molecules, fullerenes are
made from carbon atoms joined together to make tubes and cages.
(The prefix NANO means that everything is on a very small scale)
69. ANOTHER FORM OF CARBON
NANOSCIENCE
Refers to the science of structures that are 1–100nm in size
Nanoparticles Show different properties to the same materials in bulk
and have a high surface area to volume ratio
This can lead to the development of…
new computers
new catalysts
new coatings
stronger and lighter construction materials
new cosmetics such as sun-tan creams and deodorants
Scientifically, NANO means one thousand millionth (10-9)
70. ANOTHER FORM OF CARBON
FULLERENES
Although not officially classed as giant molecules, fullerenes are
made from carbon atoms joined together to make tubes and cages.
NANOTUBES These are fullerenes where hexagonal sheets of carbon atoms
have been rolled into a tube – a bit like ‘chicken wire’
71. ANOTHER FORM OF CARBON
FULLERENES
Although not officially classed as giant molecules, fullerenes are
made from carbon atoms joined together to make tubes and cages.
NANOTUBES These are fullerenes where hexagonal sheets of carbon atoms
have been rolled into a tube – a bit like ‘chicken wire’
sheets can be ‘rolled’
to form tubes
72. ANOTHER FORM OF CARBON
FULLERENES
Although not officially classed as giant molecules, fullerenes are
made from carbon atoms joined together to make tubes and cages.
NANOTUBES These are fullerenes where hexagonal sheets of carbon atoms
have been rolled into a tube – a bit like ‘chicken wire’
very strong useful where lightness and strength are needed
eg tennis racket frames
73. ANOTHER FORM OF CARBON
FULLERENES
Although not officially classed as giant molecules, fullerenes are
made from carbon atoms joined together to make tubes and cages.
NANOTUBES These are fullerenes where hexagonal sheets of carbon atoms
have been rolled into a tube – a bit like ‘chicken wire’
very strong useful where lightness and strength are needed
eg tennis racket frames
conductors of used as semiconductors in electronic circuits
electricity
74. ANOTHER FORM OF CARBON
FULLERENES
Although not officially classed as giant molecules, fullerenes are
made from carbon atoms joined together to make tubes and cages.
NANOTUBES These are fullerenes where hexagonal sheets of carbon atoms
have been rolled into a tube – a bit like ‘chicken wire’
very strong useful where lightness and strength are needed
eg tennis racket frames
conductors of used as semiconductors in electronic circuits
electricity
tubular can be used to transport a drug into the body
structure
drug molecules can be put inside the nanotube which
holds the drug until it gets to where it is needed
75. ANOTHER FORM OF CARBON
FULLERENES
Although not officially classed as giant molecules, fullerenes are
made from carbon atoms joined together to make tubes and cages.
NANOTUBES These are fullerenes where hexagonal sheets of carbon atoms
have been rolled into a tube – a bit like ‘chicken wire’
very strong useful where lightness and strength are needed
eg tennis racket frames
conductors of used as semiconductors in electronic circuits.
electricity
tubular can be used to transport a drug into the body
structure
drug molecules can be put inside the nanotube which
holds the drug until it gets to where it is needed
76. ANOTHER FORM OF CARBON
BUCKMINSTERFULLERENE
A fullerene where the carbon atoms are arranged in a ball shape molecule
C60 Sixty carbon atoms are arranged in a ball in rings of 5 and 6
It is a bit like the arrangement of panels in a football
77. GIANT COVALENT MOLECULES
SILICA
MELTING POINT VERY HIGH
many covalent bonds must be broken to separate atoms
STRENGTH STRONG
each silicon atom is joined to four oxygen atoms
each oxygen atom is joined to two silicon atoms
ELECTRICAL NON-CONDUCTOR – no mobile electrons
silicon atoms
oxygen atoms
