Presentazione di PowerPoint

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Crystals and Symmetry in Crystalline Structures
Aims To analyse the general characteristics of
solids relations between aggregation state and
internal structure To describe properties of
crystalline and vitreous structures To recognise
symmetry in crystalline structures
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Amorphous structures in everyday life
Glass
Plastic material
Obsidian
Polycrystalline structures in everyday life
A marble working top in the kitchen
rock-salt
Crystals in everyday life
Incrustations of a boiler
Ice crystal
Diamond needle of a record player
Crystals of vitamine C
Silver nitrate
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The internal structure determines all the
chemical and physical properties of crystals
Crystal the periodic 3D repetition of
elementary cells fill the entire volume
Crystalline Structure
Polycrystal made up of periodic parts
Polycrystalline Structure
Amorphous Structure
Amorphous it is not periodic
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Practical Activity Observation and formation of
crystals by evaporation
Crystal growing experiments
The elementary cells are placed tidily one next
to the other and the crystal can increase
similarly to the building of a skyscraper. (e.g.
Potassium alum sugar epsom salts sodium
chloride sodium nitrate)
Potassium alum
Solution of potassium alum
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The Shape of Crystals
We discover that what we see on a large scale is
due to the repetition of elementary shapes, as
occurs in building with Lego.
At an atomic level
At a macroscopic level
Practical Activity Lets build models of
crystalline networks
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rock salt
pyrite
fluorite
Lets observe some crystalline structures
    What symmetries can you see?
mica
blende
quartz
Università degli Studi di Ferrara, Dipartimento
di Scienze della Terra
olivine
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Cubic System
Lets discover and identify some simple systems,
e. g.
Hexagonal System
Rhombic System
Fluorite
Pyrite
Rocksalt
Blende
Olivine
Mica
.
Quartz
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Practical Activity Lets build models of
regular solids, their axes and planes of symmetry
(e. g. a cube)