Ryan Ali M. CatagaChemistrySir Joel

The angles between the surfaces are always exactly 90 degrees.

This idea began with NICOLAUS STENO in the late 1669

His observations have been extended to Intensive Properties

Sample FillSample FillExtensive Propersties of Crystals may vary

Sample FillSample FillWhile intensive properties remain the same

A rigid bodies in which the particles are arranged in units which form a repeating pattern

The study of Solid State is the study of Crystals

They can’t be seen in our eyes

All crystals are made with similar small units

Crystals form by repetition of identical units

CRYSTALS HAVE SEVEN SHAPES

0

1

2

3

4

5

1669 1788 1983 2012

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Length of the Unit Cell Axes

Angles Between the Unit Cell Axes

Crystal System

All equal All = 90 degrees Cubic

2 Equal1 Unequal

All = 90 degrees Tetragonal

3 Equal1 Unequal

1 = 90 degrees3 = 60 degrees

Hexagonal

All equal All ≠ 90 degrees Rhombohedral

All unequal All = 90 degrees Orthorombhic

All unequal 2 = 90 degrees1 = ≠ 90 degrees

Monoclinic

All unequal All ≠ 90 degree Triclinic