Solids

1
Solids Crystals

• Katie McShay, Clare McNelly, Kate Greenhalgh,
  Colleen Martin

2
Topics to be Covered

• Solids
• Structure and Characteristics
• Heating Solids
• Melting/Freezing Points

• Crystals
• Structure
• Shape
• Seven Groups
• Diagrams

3
Two Types of Solids

• 2 types of solids are
• Crystalline
• Crystalline solids are arranged in fixed
  geometric patterns
• Examples of crystalline solids are ice, methanol,
  and sodium chloride
• Amorphous
• Amorphous solids are solids with random
  unoriented molecules.
• Examples of amorphous solids are glass and
  plastic

4
Structure of Solids

• Particles
• packed closely together
• in a regular pattern
• Dense and incompressible
• Fixed volume and shape
• Dont flow easily

5
Heating Solids

• Expand when heated
• Particles vibrate faster
• Increase in kinetic energy
• Organization of particles break down
• ? in volume, ? in density

6
Melting Point

• The temperature at which a solid turns into a
  liquid ( Solid ? Liquid)
• Ionic solids
• High melting points
• Molecular solids
• Low melting points

7
Freezing Point

• Reversing the melting process
• Liquid ? Solid
• Melting/Freezing points
• Same temperature

8
Crystal Structure

• Most solid substances are crystalline
• Made of
• - atoms
• - ions
• - molecules
• Arranged in orderly, repeating, 3D pattern
  called crystal lattice

9
Shape of Crystals

• Shape depends on
• arrangement of particles
• All have a regular shape
• Reflects arrangement of the particles within the
  crystal
• Type of bonding between atoms determines the
  melting points of crystals
• Crystals have sides or faces

10
Diamond Carbon Crystal Atom
Diamond each carbon atom in the interior of the
diamond is strongly bonded to four others.
Diamond is the hardest known material.
11
Graphite Carbon Crystal Atom
Graphite the carbon atoms are linked in widely
spaced layers of hexgonal (six-sided) arrays.
Weak bonds between these layers allow them to
slide over one another, making graphite very soft.
12
Buckminsterfullerene Carbon Crystal Atom

• Buckminsterfull-erene 60 carbon atoms form a
  hollow sphere the carbons are arranged in
  pentagons and hexagons as on a soccer ball.

13
Seven Crystal Systems

• Differ in terms of
• the angles between the faces
• the number of edges of equal length on each face.

• Seven Systems
• Cubic
• Tetragonal
• Orthorhombic
• Monoclinic
• Triclinic
• Hexagonal
• Rhombohedral

14
Unit Cells

• Smallest group of particles within a crystal
• Retains the geometric shape of the crystal
• Crystal lattice- repeating array of any 1 of 14
  kinds of unit cells
• Each crystal system has 1-4 types of unit cells
  associated with that system

FCC face-centered cubic BCC body-centered cubic
15
References

• http//www.madsci.org/posts/archives/may97/8598171
  33.Ch.r.html
• http//www.chem.purdue.edu/gchelp/liquids/characte
  r.html
• http//www.wpbschoolhouse.btinternet.co.uk/page03/
  3_52states.htm
• www.paxcam.com/imgs/library/18/crystals.jpg
• www.matter.org.uk/.../images/cubic-crystals.gif
• http//www.utmem.edu/physpharm/.003a.html
• http//images.google.com/images?hlenqgraphitec
  arbonatombtnGSearchImages
• http//images.google.com/images?svnum10hlenqb
  uckminsterfullerenecarbonatombtnGSearch
• http//images.google.com/images?svnum10hlenqd
  iamondcarbonatom
• http//www.utmem.edu/physpharm/.003a.html