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Chapter 2 Minerals.

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Presentation on theme: "Chapter 2 Minerals."— Presentation transcript:

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

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