Chapter 2Chapter 2

MineralsMinerals

MatterMatter

Solid – rocks and Solid – rocks and mineralsminerals

Liquid – oceans, Liquid – oceans, rivers, lakesrivers, lakes

Gas – atmosphereGas – atmosphere Nearly 4000 Nearly 4000

minerals on Earthminerals on Earth Building blocks – Building blocks –

elementselements

Elements and the Periodic TableElements and the Periodic Table

Copper, iron, silver, goldCopper, iron, silver, gold Element – substance that cannot be Element – substance that cannot be

broken down into simpler substances broken down into simpler substances by chemical or physical meansby chemical or physical means

112 known, 92 naturally occurring 112 known, 92 naturally occurring Rows – periodsRows – periods

– Share maximum electrons in outer shellShare maximum electrons in outer shell Columns – groupsColumns – groups

– Have similar propertiesHave similar properties

Elements and the Periodic TableElements and the Periodic Table

8 known elements make up most of 8 known elements make up most of Earth’s crustEarth’s crust– Oxygen (O)Oxygen (O)– Silicon (Si)Silicon (Si)– Aluminum (Al)Aluminum (Al)– Iron (Fe)Iron (Fe)– Calcium (Ca)Calcium (Ca)– Sodium (Na)Sodium (Na)– Potassium (K)Potassium (K)– Magnesium (Mg)Magnesium (Mg)

AtomsAtoms

Atom – smallest particle of matter Atom – smallest particle of matter that contains characteristics of an that contains characteristics of an elementelement– Nucleus – protons(+) and neutrons(=)Nucleus – protons(+) and neutrons(=)

Proton and neutron have about equal massProton and neutron have about equal mass

– Atomic number – number of protons in Atomic number – number of protons in the nucleusthe nucleus

– Atoms have same number of protons Atoms have same number of protons and neutronsand neutrons

AtomsAtoms

How do we figure How do we figure out number of out number of neutrons?neutrons?

Atomic mass Atomic mass minus (-) # of minus (-) # of protons (atomic protons (atomic number)number)

4.003 – 2 + 2 4.003 – 2 + 2 neutronsneutrons

How many neutrons?How many neutrons?

How many protons are in this atom?

What is its mass number?

How many neutrons does it have?

AtomsAtoms

ElectronsElectrons – smallest of three – smallest of three fundamental particlesfundamental particles– Located in energy levels – sphere Located in energy levels – sphere

shaped negative zone called shaped negative zone called electron electron cloudcloudfirst energy level – 2 electronsfirst energy level – 2 electronsSecond energy level – 8 electronsSecond energy level – 8 electrons

– Interactions among energy levels Interactions among energy levels explains why atoms form compoundsexplains why atoms form compounds

AtomAtom

IsotopesIsotopes

Isotopes – atoms with same number Isotopes – atoms with same number of protons but different numbers of of protons but different numbers of neutronsneutrons– Labeled using mass numberLabeled using mass number

Mass number – total mass of an atom Mass number – total mass of an atom (protons + neutrons)(protons + neutrons)

Expressed in atomic mass unitsExpressed in atomic mass units

– Radioactive decay – occurs with some Radioactive decay – occurs with some isotopes whose nuclei are unstableisotopes whose nuclei are unstableCan be used to determine the ages of Can be used to determine the ages of

fossils, rocks and mineralsfossils, rocks and minerals

IsotopesIsotopes

Carbon has 15 Carbon has 15 different isotopesdifferent isotopes

Carbon 14 most Carbon 14 most commonly used for commonly used for radioactive datingradioactive dating

Why Atoms BondWhy Atoms Bond

Compounds – substance that consists of two or Compounds – substance that consists of two or more elements that are chemically combined in more elements that are chemically combined in specific proportionsspecific proportions– Form when atoms are more stable in a combined Form when atoms are more stable in a combined

formform– They gain, lose, or share electronsThey gain, lose, or share electrons– Most stable elements – far right of periodic tableMost stable elements – far right of periodic table

Group 8AGroup 8A Outer shell is filledOuter shell is filled

– Atom undergoes changes to its electron structure Atom undergoes changes to its electron structure to be more like atoms in Group 8Ato be more like atoms in Group 8A

Chemical BondsChemical Bonds

Chemical Bonds – forces that hold Chemical Bonds – forces that hold atoms together in a compoundatoms together in a compound– IonicIonic– CovalentCovalent– Metallic Metallic

Properties of a compound are Properties of a compound are different than properties of elements different than properties of elements in a compoundin a compound

Ionic BondsIonic Bonds

Ionic Bonds – form between positive Ionic Bonds – form between positive and negative ionsand negative ions– Ion – atom that has an electrical charge Ion – atom that has an electrical charge

because of gain or loss of one or more because of gain or loss of one or more electronselectronsAtoms that lose electrons – positively Atoms that lose electrons – positively

chargedchargedAtoms that gain electrons – negatively Atoms that gain electrons – negatively

chargedcharged

Ionic BondsIonic Bonds Some compounds Some compounds

have mineral name have mineral name and chemical nameand chemical name– NaCl – sodium NaCl – sodium

chloride; halitechloride; halite Na loses one Na loses one

electron – becomes electron – becomes + ions+ ions

Cl gains one electron Cl gains one electron

– becomes – ions– becomes – ions – Becomes table saltBecomes table salt

Ionic BondsIonic Bonds

Elements with ionic bonds – ionic Elements with ionic bonds – ionic compoundscompounds– Rigid solids with high melting and boiling Rigid solids with high melting and boiling

pointspoints– Poor conductors of electricity in solid statePoor conductors of electricity in solid state– When melted, great conductors of electricityWhen melted, great conductors of electricity

Most contain elements from groups 1 & 2 Most contain elements from groups 1 & 2 reacting with groups 16 & 17reacting with groups 16 & 17

Covalent BondsCovalent Bonds

Covalent bonds – form when atoms Covalent bonds – form when atoms share electronsshare electrons– Have low melting and boiling pointsHave low melting and boiling points– Poor conductors of electricityPoor conductors of electricity

– Silicon dioxide (SiOSilicon dioxide (SiO22) – quartz) – quartzOne of most common covalent bonds on One of most common covalent bonds on

EarthEarthOne silicon and two oxygen atoms share One silicon and two oxygen atoms share

electrons in outer shellelectrons in outer shell

Covalent BondCovalent Bond

Covalent BondsCovalent Bonds

Molecule – smallest particle of a Molecule – smallest particle of a covalent compound that shows covalent compound that shows properties of that compoundproperties of that compound– Water – HWater – H22O moleculesO molecules

Two hydrogen atoms covalently bonded to Two hydrogen atoms covalently bonded to an oxygenan oxygen

– Atmospheric gases - hydrogen, oxygen, Atmospheric gases - hydrogen, oxygen, nitrogen, and carbon dioxide nitrogen, and carbon dioxide consist of moleculesconsist of molecules

Metallic BondsMetallic Bonds

Metallic bonds – form when electrons Metallic bonds – form when electrons are shared by metal ionsare shared by metal ions– Sharing of electron pool gives metals Sharing of electron pool gives metals

their characteristic propertiestheir characteristic propertiesMalleable – easily shapedMalleable – easily shapedDuctile – drawn into thin wires without Ductile – drawn into thin wires without

breakingbreakingExcellent conductors of electricityExcellent conductors of electricity

MineralsMinerals

MineralMineral– Naturally occurringNaturally occurring– Solid substanceSolid substance– Orderly crystalline structureOrderly crystalline structure– Definite chemical compositionDefinite chemical composition– Generally considered inorganicGenerally considered inorganic

Crystalline StructureCrystalline Structure

How Minerals FormHow Minerals Form

Crystallization from Crystallization from MagmaMagma– Magma cools – Magma cools –

elements combine elements combine to form mineralsto form minerals

How Minerals How Minerals FormForm

PrecipitationPrecipitation– When water When water

evaporates – evaporates – substances react to substances react to form mineralsform minerals

– Changes in Changes in temperature – can temperature – can cause substances to cause substances to precipitate and precipitate and form mineralsform minerals

How Minerals FormHow Minerals Form

Pressure and TemperaturePressure and Temperature– Increase in pressure: can cause mineral Increase in pressure: can cause mineral

to recrystallize while still solidto recrystallize while still solidAtoms rearranged to form more compact Atoms rearranged to form more compact

mineralsminerals

– Change in temp: cause certain minerals Change in temp: cause certain minerals to become unstableto become unstableNew minerals form that are stable at that New minerals form that are stable at that

temptemp

Meteor Crater - ArizonaMeteor Crater - Arizona

Quartz sandstone Quartz sandstone – at 500,000 psi is – at 500,000 psi is converted to converted to coesitecoesite

Meteor impact Meteor impact creates pressurecreates pressure

11stst time element time element found in naturefound in nature

How Minerals FormHow Minerals Form

Hydrothermal Hydrothermal solutionssolutions– Very hot mixture of Very hot mixture of

water and dissolved water and dissolved substancessubstances

When they come When they come into contact with into contact with existing minerals – existing minerals – new minerals formednew minerals formed

Mineral GroupsMineral Groups

Minerals – classified based on Minerals – classified based on compositioncomposition

Silicates – most common groupSilicates – most common group– Silicon and oxygen Silicon and oxygen

Forms a silicon-oxygen tetrahedronForms a silicon-oxygen tetrahedronOne silicon and 4 oxygen atoms forms One silicon and 4 oxygen atoms forms

frameworkframework

– Most form from magma crystallizationMost form from magma crystallizationSome from weatheringSome from weathering extreme pressures from mountain buildingextreme pressures from mountain building

QuartzQuartz

SilicatesSilicates

Different forms:Different forms:– Single tetrahedron: olivineSingle tetrahedron: olivine– Single chains: augiteSingle chains: augite– Double chains: hornblendeDouble chains: hornblende– Sheets: micaSheets: mica– Three-dimensional networks: quartz, Three-dimensional networks: quartz,

feldsparfeldspar

SilicatesSilicates

CarbonatesCarbonates

Second most common mineral groupSecond most common mineral group Carbon, oxygen, and one or more Carbon, oxygen, and one or more

metallic elementsmetallic elements– Calcite (CaCOCalcite (CaCO33) most common) most common

– Dolomite – magnesium and carbonDolomite – magnesium and carbon– Limestone and marble Limestone and marble – Used for building and constructionUsed for building and construction

LimestoneLimestone

OxidesOxides

Oxygen and one or more elements, Oxygen and one or more elements, usually metalsusually metals– Some form from magma crystallizationSome form from magma crystallization– Some form due to changes in temp and Some form due to changes in temp and

pressurepressureRutile (TiORutile (TiO22) – titanium oxide) – titanium oxide

Corundum (AlCorundum (Al22OO33) – aluminum oxide) – aluminum oxide

Hematite (FeHematite (Fe22OO33) – iron oxide) – iron oxide– Existing minerals exposed to liquid water or Existing minerals exposed to liquid water or

moisture in the airmoisture in the air

Sulfates and SulfidesSulfates and Sulfides

Contain element sulfurContain element sulfur SulfatesSulfates

– Anhydrite (CaSOAnhydrite (CaSO44))– Gypsum (CaSOGypsum (CaSO4 4 · 2H· 2H22O)O)– Form when mineral-rich waters evaporateForm when mineral-rich waters evaporate

SulfidesSulfides– Galena (PbS)Galena (PbS)– Sphalerite (ZnS)Sphalerite (ZnS)– Pyrite (FeSPyrite (FeS22) – ) –

““Fool’s Gold”, WWII sulfuric acid, car battery, Fool’s Gold”, WWII sulfuric acid, car battery, explosivesexplosives

– Form from thermal, or hot-water, solutionsForm from thermal, or hot-water, solutions

Largest known Largest known crystals in the worldcrystals in the world

Naica Mine, Naica Mine, MexicoMexico

GypsumGypsum Up to 50 ft. Up to 50 ft.

long, 4 feet long, 4 feet in diameterin diameter

HalidesHalides

Contain a halogen ion plus one or Contain a halogen ion plus one or more other elementsmore other elements– Halogens – elements from Groups 7A of Halogens – elements from Groups 7A of

periodic tableperiodic table Includes Fluorine (F) , chlorine (Cl)Includes Fluorine (F) , chlorine (Cl)

– Halite – NaCl: table saltHalite – NaCl: table salt

– Fluorite – CaFFluorite – CaF22: makes steel: makes steelForms when salt water evaporatesForms when salt water evaporates

HaliteHalite

Native ElementsNative Elements

Minerals that exist in relatively pure formMinerals that exist in relatively pure form– Gold (Au)Gold (Au)

Jewelry, moneyJewelry, money

– Silver (Ag)Silver (Ag)– Copper (Cu)Copper (Cu)

Electrical wiring, computersElectrical wiring, computers

– Sulfur (S)Sulfur (S)– Carbon (C)Carbon (C)

diamond and graphitediamond and graphite– Drill bits, abrasivesDrill bits, abrasives

– Some form from hydrothermal solutionsSome form from hydrothermal solutions