CH2 topic 5 Solid structure and smart materials

structure of graphite diamond iodine metals smart materials nanoparticles. I closely followed the revision guide here as it is a more knowledged based unit thqan understanding I also used the Chem guide site

HideShow resource information
  • Created by: Olivia
  • Created on: 25-05-11 14:32
Preview of CH2 topic 5 Solid structure and smart materials

First 291 words of the document:

Topic 5 solid structure
(a) recall and describe the crystal structures of sodium chloride and caesium chloride,
including the crystal coordination numbers and a simple explanation of the
differences in terms of the relative sizes of the cations
Cs+ has a larger ionic radius the Na+
therefore caesium can accommodate more Cl ions
Sodium chloride has 6:6 coordination and is a face
centred cube
each sodium ion is surrounded by 6 neighbouring chloride ions
Caesium chloride has 8:8
coordination
It has a structure made up of two
interpenetrating simple cubic structures
(b) recall and describe the structures of diamond and graphite and know that iodine forms
a molecular crystal
In diamond the carbon atoms are bonded tetrahedrally in
the lattice. Each carbon atom is bonded covalently to four
other carbon atoms.
The fact that this tetrahedral bonding forms a rigid
structure accounts for the hardness of diamond and the
fact that it does not conduct electricity (all four of the
atoms outer electrons are involved in covalent bonding).
Is insoluble in water and organic solvents. There are no
possible attractions which could occur between
solvent molecules and carbon
atoms which could outweigh the attractions
between the covalently bound carbon atoms.
In graphite each carbon atom is bonded to
three other carbon atoms in a planar structure.
The planes of carbon atoms can slide over each
other.
temporary dipoles are set up by the delocalised
electrons meaning the planes are held together by van
der Waals.
both graphite and diamond have high melting
points as they are giant covalent.

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Iodine, I2
Iodine is a dark grey crystalline solid with a purple vapour. M.Pt: 114°C. B.Pt: 184°C.
It is very, very slightly soluble in water, but dissolves freely in organic solvents.
Iodine is therefore a low melting point solid. The crystallinity suggests a regular
packing of the molecules.
The structure is described as face centred cubic - it is a cube of iodine molecules
with another molecule at the centre of each face.…read more

Page 3

Preview of page 3

Here's a taster:

H, etc) and this is often caused by a
change in structure
Smart materials are new materials whose properties change reversibly with a
change in conditions such as mechanical deformation, change in temperature,
light, pH etc.
Shape memory polymers:
These polymers are somewhere between thermoplastics and thermosets..
Polymers can be made with shape memory characteristics. SMPs change
between rigid and elastic states by way of thermal changes.
The change takes place at what is called the glass transition temperature.…read more

Page 4

Preview of page 4

Here's a taster:

H.
Possible applications could be
Artificial muscles
Underground water cut off in the oil industry.
The volume of gel can be pH controlled.
(g) understand that nanosized materials often exhibit different properties which can lead
to new uses.
These are often defined as particulate materials with at least one dimension of
less than 100 nanometres (nm).
1 nanometre is 109 m.
It has been found that nanomaterials may have properties which are significantly
different from the material in bulk.…read more

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all resources »