1. Chapter 2
Minerals

2. Matter Solid – rocks and minerals Liquid – oceans, rivers, lakes
Gas – atmosphere
Nearly 4000 minerals on Earth
Building blocks – elements

3. Elements and the Periodic Table
Copper, iron, silver, gold
Element – substance that cannot be broken down into simpler substances by chemical or physical means
112 known, 92 naturally occurring
Rows – periods
Share maximum electrons in outer shell
Columns – groups
Have similar properties

4. Elements and the Periodic Table
8 known elements make up most of Earth’s crust
Oxygen (O)
Silicon (Si)
Aluminum (Al)
Iron (Fe)
Calcium (Ca)
Sodium (Na)
Potassium (K)
Magnesium (Mg)

5. Atoms
Atom – smallest particle of matter that contains characteristics of an element
Nucleus – protons(+) and neutrons(=)
Proton and neutron have about equal mass
Atomic number – number of protons in the nucleus
Atoms have same number of protons and neutrons

6. Atoms How do we figure out number of neutrons?
Atomic mass minus (-) # of protons (atomic number)
4.003 – neutrons

7. How many neutrons? How many protons are in this atom?
What is its mass number?
How many neutrons does it have?

8. Atoms Electrons – smallest of three fundamental particles
Located in energy levels – sphere shaped negative zone called electron cloud
first energy level – 2 electrons
Second energy level – 8 electrons
Interactions among energy levels explains why atoms form compounds

9. Atom

10. Isotopes
Isotopes – atoms with same number of protons but different numbers of neutrons
Labeled using mass number
Mass number – total mass of an atom (protons + neutrons)
Expressed in atomic mass units
Radioactive decay – occurs with some isotopes whose nuclei are unstable
Can be used to determine the ages of fossils, rocks and minerals

11. Isotopes Carbon has 15 different isotopes
Carbon 14 most commonly used for radioactive dating

12. Why Atoms Bond
Compounds – substance that consists of two or more elements that are chemically combined in specific proportions
Form when atoms are more stable in a combined form
They gain, lose, or share electrons
Most stable elements – far right of periodic table
Group 8A
Outer shell is filled
Atom undergoes changes to its electron structure to be more like atoms in Group 8A

13. Chemical Bonds
Chemical Bonds – forces that hold atoms together in a compound
Ionic
Covalent
Metallic
Properties of a compound are different than properties of elements in a compound

14. Ionic Bonds Ionic Bonds – form between positive and negative ions
Ion – atom that has an electrical charge because of gain or loss of one or more electrons
Atoms that lose electrons – positively charged
Atoms that gain electrons – negatively charged

15. Ionic Bonds Some compounds have mineral name and chemical name
NaCl – sodium chloride; halite
Na loses one electron – becomes + ions
Cl gains one electron – becomes – ions
Becomes table salt

16. Ionic Bonds Elements with ionic bonds – ionic compounds
Rigid solids with high melting and boiling points
Poor conductors of electricity in solid state
When melted, great conductors of electricity
Most contain elements from groups 1 & 2 reacting with groups 16 & 17

17. Covalent Bonds Covalent bonds – form when atoms share electrons
Have low melting and boiling points
Poor conductors of electricity
Silicon dioxide (SiO2) – quartz
One of most common covalent bonds on Earth
One silicon and two oxygen atoms share electrons in outer shell

18. Covalent Bond

19. Covalent Bonds
Molecule – smallest particle of a covalent compound that shows properties of that compound
Water – H2O molecules
Two hydrogen atoms covalently bonded to an oxygen
Atmospheric gases - hydrogen, oxygen, nitrogen, and carbon dioxide
consist of molecules

20. Metallic Bonds
Metallic bonds – form when electrons are shared by metal ions
Sharing of electron pool gives metals their characteristic properties
Malleable – easily shaped
Ductile – drawn into thin wires without breaking
Excellent conductors of electricity

21. Minerals Mineral Naturally occurring Solid substance
Orderly crystalline structure
Definite chemical composition
Generally considered inorganic

22. Crystalline Structure

23. How Minerals Form Crystallization from Magma
Magma cools – elements combine to form minerals

24. How Minerals Form Precipitation
When water evaporates – substances react to form minerals
Changes in temperature – can cause substances to precipitate and form minerals

25. How Minerals Form Pressure and Temperature
Increase in pressure: can cause mineral to recrystallize while still solid
Atoms rearranged to form more compact minerals
Change in temp: cause certain minerals to become unstable
New minerals form that are stable at that temp

26. Meteor Crater - Arizona
Quartz sandstone – at 500,000 psi is converted to coesite
Meteor impact creates pressure
1st time element found in nature

27. How Minerals Form Hydrothermal solutions
Very hot mixture of water and dissolved substances
When they come into contact with existing minerals – new minerals formed

28. Mineral Groups Minerals – classified based on composition
Silicates – most common group
Silicon and oxygen
Forms a silicon-oxygen tetrahedron
One silicon and 4 oxygen atoms forms framework
Most form from magma crystallization
Some from weathering
extreme pressures from mountain building

29. Quartz

31. Silicates Different forms: Single tetrahedron: olivine
Single chains: augite
Double chains: hornblende
Sheets: mica
Three-dimensional networks: quartz, feldspar

32. Silicates

33. Carbonates Second most common mineral group
Carbon, oxygen, and one or more metallic elements
Calcite (CaCO3) most common
Dolomite – magnesium and carbon
Limestone and marble
Used for building and construction

34. Limestone

35. Oxides Oxygen and one or more elements, usually metals
Some form from magma crystallization
Some form due to changes in temp and pressure
Rutile (TiO2) – titanium oxide
Corundum (Al2O3) – aluminum oxide
Hematite (Fe2O3) – iron oxide
Existing minerals exposed to liquid water or moisture in the air

36. Sulfates and Sulfides Contain element sulfur Sulfates Sulfides
Anhydrite (CaSO4)
Gypsum (CaSO4 · 2H2O)
Form when mineral-rich waters evaporate
Sulfides
Galena (PbS)
Sphalerite (ZnS)
Pyrite (FeS2) –
“Fool’s Gold”, WWII sulfuric acid, car battery, explosives
Form from thermal, or hot-water, solutions

37. Largest known crystals in the world
Naica Mine, Mexico
Gypsum
Up to 50 ft. long, 4 feet in diameter

38. Halides Contain a halogen ion plus one or more other elements
Halogens – elements from Groups 7A of periodic table
Includes Fluorine (F) , chlorine (Cl)
Halite – NaCl: table salt
Fluorite – CaF2: makes steel
Forms when salt water evaporates

39. Halite

40. Native Elements Minerals that exist in relatively pure form Gold (Au)
Jewelry, money
Silver (Ag)
Copper (Cu)
Electrical wiring, computers
Sulfur (S)
Carbon (C)
diamond and graphite
Drill bits, abrasives
Some form from hydrothermal solutions