Atoms, Compounds, Minerals and Rocks

1
Atoms, Compounds,Minerals and Rocks
2
Atoms

• Atoms - the smallest unit of an element that
  retains the physical and chemical properties of
  that element
• Made up of a nucleus, and a cloud of
  electrons
• Nucleus made up of protons and neutrons
• Number of protons determines which type of
  Element the atom is
• Element - distinctive type of matter with
  specific phyisical and chemical properties
• Examples Iron, Oxygen, Hydrogen, etc.
• Generally grouped as Metals or Nonmetals

3
Compounds

• Compound - substances made by the bonding of
  chemical elements (from chemical reactions).
  Compounds are comprised of two or more different
  elements.
• Chemical bonds may be made by
• sharing electrons between atoms - covalent
  bonds
• lending or borrowing electrons with mutual
  attraction of oppositely charged atoms - ionic
  bonds
• The properties of compounds are dramatically
  different from those of the elements that
  comprise them

4
A Mineral is

• Naturally occurring
• Inorganic (not made from animals or plants)
• Solid
• with a definite chemical composition (formula)
• and an orderly arrangement of atoms (crystal
  structure)
• Minerals are chemical compounds

5
(No Transcript)
6
Crystal Structure

• How do crystals form?
• Atoms must be free to move
• Chemical bonds dictate the geometric arrangement
  of atoms
• Crystal is external manifestation of order at
  atomic level

7
Crystal Structure

• Atoms must be free to move
• Under what conditions does this occur?
• In a melt (magma)
• In solution (dissolved in water)

8
Abundance of chemical elements in Earths Crust

• O 46.6 Si 27.7
• Al 8.1 Fe 5.0
• Ca 3.6 Na 2.8
• K 2.6 Mg 2.1
• Other 1.7

9
Silicate Minerals

• O and Si make up nearly 75 of crust
• Most common elements should make up most common
  minerals
• Common rock-forming minerals are silicates
• Silicates have Si, O and other elements such as
  Fe, Mg, Al, Na, K, Ca

10
Silicon-Oxygen Tetrahedron

• Building Block of Silicate minerals
• Si surrounded by 4 O
• O may be shared so that tetrahedra link together

11
Sharing Tetrahedra
12
Olivine Fe,Mg silicateSingle Tetrahedra
13
Pyroxene Fe, Mg, Al silicateSingle Chains
14
Amphibole Fe, Mg, Ca, Na, Al, F silicate
15
Micas (biotite, muscovite) K, Al /-Ca, Mg, Fe
silicates
16
Complex silicates

• Quartz SiO2
• Feldspars
• Na,Ca silicates Plagioclase
• K, Al silicates
• Other minerals

17
Bowens Reaction Series
18
Other Mineral Families

• Halides contain metals and Cl, F, I, etc.
• Carbonates contain metals and CO3
• Oxides/Hydroxides contain metals and O or OH
• Sulfides contain metals and S
• Phosphates contain metals and PO4
• Native Elements pure elements

19
So, What is a Rock?

• A Rock is
• An aggregate of minerals
• Usually, a mixture of two or more minerals, each
  of which remains distinct