Minerals Building Blocks of Rocks
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Transcript of Minerals Building Blocks of Rocks
MineralsBuilding Blocks of Rocks
What makes minerals and rocks ?What makes minerals and rocks ?
Fe, Mg, Si, O, K chemical compounds igneous, sedimentary, metamorphic
silicon (Si)silicon (Si)
oxygen (O)oxygen (O)
iron (Fe)iron (Fe)
quartzquartz
orthoclaseorthoclase
biotitebiotite
granitegranite
sandstonesandstone
gneissgneiss
ElementsElements MineralsMinerals RocksRocks
The basic atom model (inside the atom)Protons Protons Electrons Electrons Neutrons Neutrons N
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electron shellselectron shells Atomic numberAtomic number• number of protonsnumber of protons• determines chemicaldetermines chemical characteristicscharacteristics• range from 1 (H) torange from 1 (H) to 92 (Ur)92 (Ur)+++
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Atomic massAtomic mass• protons + neutronsprotons + neutrons• neutrons add “atomicneutrons add “atomic weight”weight”• same atom can havesame atom can have varying number of varying number of neutrons-- isotopesneutrons-- isotopes
nucleusnucleus
Germanium atoms (Gr)cobalt (Co) atoms bonding with copper (Cu) atoms
silicon + oxygensilicon + oxygen(silicate tetrahedron)(silicate tetrahedron)
Oxygen (4)Oxygen (4)
Silicon (1)
Elements and the Periodic Table (PT)Elements and the Periodic Table (PT)ELEMENTSELEMENTS
• Considered a pure substanceConsidered a pure substance• each element has its own atomic numbereach element has its own atomic number
• About 118 known elements (92 natural, 26 synthetic)About 118 known elements (92 natural, 26 synthetic)• Elements possess distinctive physical propertiesElements possess distinctive physical properties
• hardness, boiling points hardness, boiling points • solid, liquid, or gassolid, liquid, or gas
increasing atomic increasing atomic numbersnumbers
Groups similarproperties
Periods
Non-metals
Non-metals
Metalloids
Metalloids
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Interpreting the PT-Interpreting the PT-
7979AuAu197.0197.0
GoldGold
Atomic numberAtomic number• number of protonsnumber of protonsElemental symbolElemental symbolAtomic weightAtomic weight• protons + neutronsprotons + neutrons
Element nameElement name
So, observing the PT patterns and the definition of an element,So, observing the PT patterns and the definition of an element, what characteristics distinguish one element from another?what characteristics distinguish one element from another?
Why is an element considered a pure substance????Why is an element considered a pure substance????
I I Earth Science better the secondEarth Science better the second week. week.
I will get an A on my exams and quizzes.I will get an A on my exams and quizzes.
Discuss with a friend:Discuss with a friend: 1.1.What are the parts of an atom? – beWhat are the parts of an atom? – be specific (sub-atomic parts).specific (sub-atomic parts).2. How would you describe a chemical2. How would you describe a chemical element?element?3. What distinguishes one element from3. What distinguishes one element from another?another?
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Bonding the atoms (elements)Bonding the atoms (elements) Atoms bond using Atoms bond using
electrons found at the electrons found at the most outer electron most outer electron energy shellenergy shell ( (valence valence shell)shell)
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eValence shellValence shell
Electrons enter higher shell levels afterElectrons enter higher shell levels afterlower shell levels have been filled.lower shell levels have been filled.
Electrons will either be Electrons will either be sharedshared or or transferredtransferred to other atoms to other atoms at at the the valence shell.valence shell.
The atom wants to be satisfied or The atom wants to be satisfied or stablestableby filling the electron shells to capacity.by filling the electron shells to capacity.Electrons are Electrons are lostlost OR OR gainedgained when whensatisfying the outer shell (valence shell).satisfying the outer shell (valence shell).
IonsIons – – the net electric charge of the atomthe net electric charge of the atom• loses an electron (positive charge)loses an electron (positive charge)• gains an electron (negative charge)gains an electron (negative charge)• equal number of electrons/protonsequal number of electrons/protons (electrically balanced – neutral)(electrically balanced – neutral)• Cation (+ ions), Anions (-) ionsCation (+ ions), Anions (-) ions
Combining Elements (Atoms) to Make MineralsCombining Elements (Atoms) to Make MineralsElements are bonded through “electrical glue” using electronsElements are bonded through “electrical glue” using electronsfrom various element configurations that form chemical from various element configurations that form chemical compounds. Compounds display completely different physicalcompounds. Compounds display completely different physicalproperties.properties.Example:Example:
+ + NaClNaClNaNa ClCl
• sodium (Na)sodium (Na)• metallicmetallic• softsoft• explosiveexplosive• lethal!lethal!
• chlorine (Cl)chlorine (Cl)• yellow gasyellow gas• lethal!lethal!
• halitehalite• new propertiesnew properties• compoundcompound• can eat itcan eat it• we need itwe need it
Bonding the elementsBonding the elements – the force that holds the – the force that holds the atoms together in a chemical compoundatoms together in a chemical compound
Types of bonding (atomic bonds)Types of bonding (atomic bonds)• Ionic bondingIonic bonding• Covalent bondingCovalent bonding• Metallic bondingMetallic bonding• Van der Waals bondingVan der Waals bonding
The Ionic BondThe Ionic Bond – – electrically transferred electrically transferred electronselectrons
+NaNa
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= NaClNaCl
Sodium ion wants toSodium ion wants toloselose the electron the electron (+) positive charge ion(+) positive charge ion
Chlorine ion wants toChlorine ion wants togaingain the electron the electron(-) charged ion(-) charged ion
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ClCl
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The Ionic BondThe Ionic Bond• moderate strength and hardnessmoderate strength and hardness• weak bond (salt dissolves in water)weak bond (salt dissolves in water)
1 = valence shell1 = valence shell 7 = valence shell7 = valence shell
Mineral examplesMineral examples• halite (table salt)halite (table salt)• biotitebiotite
Gain or shareelectrons at the valence shell
NaCl = Halite (Salt)NaCl = Halite (Salt)
Loses electrons at theLoses electrons at thevalence shellvalence shell(+) charged ions(+) charged ions
(-) charged ions
The Covalent BondThe Covalent Bond – – sharing sharing electronselectrons
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The DiamondThe Diamond““perfect geometry”perfect geometry”
The Covalent BondThe Covalent Bond•the strongest bondthe strongest bond•most minerals will scratch glassmost minerals will scratch glass•extremely hard to break the bondsextremely hard to break the bonds
Metallic bondingMetallic bonding – – tightly packed atoms “stick”tightly packed atoms “stick”to each other (a form of sharing). Outermost electronsto each other (a form of sharing). Outermost electrons(loosely held) freely move from one atom to the next.(loosely held) freely move from one atom to the next.
• good conductors of heat andgood conductors of heat and electricityelectricity• heavy “dense”heavy “dense”• malleable (metals bend easily)malleable (metals bend easily)• polish easilypolish easily
Examples of metallic minerals:Examples of metallic minerals:
galena (PbS)galena (PbS) pyrite (Fepyrite (Fe22S)S) gold (Au)gold (Au)
Van der Waals bondingVan der Waals bonding – – weak attraction betweenweak attraction betweenelectrically neutral molecules; (+) end of the moleculeelectrically neutral molecules; (+) end of the moleculeis attracted to the (-) end of the molecule.is attracted to the (-) end of the molecule.
Carbon atoms
Covalentbonds
Van derWaals bonds
• very weak bondsvery weak bonds
• easily brokeneasily broken
• “ “layers” slip past onelayers” slip past one anotheranother
Graphite exampleGraphite example
So, why do graphite and diamond displaydifferent physical properties (hardness???)—They are both composed of carbon. 1818
I I Earth Science. Earth Science.
I will get an A on my exams and quizzes.I will get an A on my exams and quizzes.
Discuss with a friend:Discuss with a friend: 4. What part of the atom bonds together4. What part of the atom bonds together to form compounds?to form compounds?
5. Explain the differences between 5. Explain the differences between ionicionic, , covalentcovalent, , metallicmetallic, and Van der, and Van der Waals bondsWaals bonds. .
What objects below do you think are What objects below do you think are minerals??minerals??
GoldGoldGasolineGasolineDiamondDiamond
WaterWaterWoodWood
What are Minerals?What are Minerals?
Why are Why are goldgold, , pyritepyrite, , andand diamonddiamond considered minerals? considered minerals?
The 5-part mineral definition:The 5-part mineral definition:• Naturally occurringNaturally occurring• Inorganic (non-living)Inorganic (non-living)• Homogeneous – solidHomogeneous – solid• Definite chemical compositionDefinite chemical composition• Definite crystalline internal structureDefinite crystalline internal structure
• 4,000 different minerals (fits 5-part 4,000 different minerals (fits 5-part definition)definition) • 25 common minerals combined to form 25 common minerals combined to form rocksrocks
I I Earth Science. Earth Science.
I will get an A on my exams and quizzes.I will get an A on my exams and quizzes.
Discuss with a friend:Discuss with a friend:6. What is the “5-part definition” of a6. What is the “5-part definition” of a mineral?mineral?7. Name 3 substances that are NOT 7. Name 3 substances that are NOT minerals and 3 substances that areminerals and 3 substances that are minerals.minerals.8. Is ice a mineral? Is water a mineral?8. Is ice a mineral? Is water a mineral? why or why not?why or why not?
What’s inside a mineralWhat’s inside a mineralA mineral’s A mineral’s crystalline structurecrystalline structure (internal geometric shape) is the (internal geometric shape) is the result of the atomic arrangement of result of the atomic arrangement of atoms (how the atoms align).atoms (how the atoms align).
Cl (Chlorine atom)Cl (Chlorine atom)
Na (Sodium atom)Na (Sodium atom)
Dependent on:Dependent on:• the size of various combining ionsthe size of various combining ions• how the ions bond togetherhow the ions bond together
Do ALL minerals “grow” and show the observer their crystalline shape? (how the atoms combine)
Fe2SPyrite
QuartzSiO2
Why do some minerals show their internal structure to the observer?
large gypsum crystalsformed 150 feet below thesurface
Enough spaceEnough timeEnough solution
Chihuahua Desert, Mexico
Crystal facesCrystal faces – – any solid body that has grown withany solid body that has grown withflat “planar” surfaces called crystal facesflat “planar” surfaces called crystal faces
• The same mineral may grow in a large, small, The same mineral may grow in a large, small, or skinny form, but the or skinny form, but the ANGLEANGLE between crystal faces between crystal faces will always remain the same. will always remain the same. • reflects the internal atomic arrangement of atomsreflects the internal atomic arrangement of atoms• proved by Danish physician- Nicolaus Steno, 1669proved by Danish physician- Nicolaus Steno, 1669• Steno’s Law states:Steno’s Law states:
The angle between any correspondingThe angle between any corresponding pairs of crystal faces of a given mineral ispairs of crystal faces of a given mineral is constant no matter what the overall shapeconstant no matter what the overall shape or size of the crystal might be.or size of the crystal might be.
Examples of atom by atom crystal growthexhibiting various angles
fat, skinny, tall, short, etc… all the same anglesfat, skinny, tall, short, etc… all the same angles
The atomic arrangement of atoms in a liquidThe atomic arrangement of atoms in a liquid• there is nonethere is none• atoms are randomly arrangedatoms are randomly arranged• an an amorphous solidamorphous solid
• a “liquid-type” solid possessing no internala “liquid-type” solid possessing no internal structurestructure• amorphous material has no melting pointamorphous material has no melting point• Example:Example: glass, plastic, waxglass, plastic, waxamorphousamorphous
structurestructure
crystallinecrystallinestructurestructure
WaxesWaxes
GlassGlassPlastic
I I Earth Science better the secondEarth Science better the second week. week.Discuss with a friend:Discuss with a friend:
9. What dictates a mineral’s crystalline9. What dictates a mineral’s crystalline structure?structure?10. What conditions must be met to form10. What conditions must be met to form perfect crystal faces?perfect crystal faces?11. Do all minerals show their crystalline11. Do all minerals show their crystalline structure to the observer (why/why not)?structure to the observer (why/why not)? 12. Describe the differences between 12. Describe the differences between amorphousamorphous and and crystallinecrystalline structures. structures.
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8 8 elements make up the rock forming elements make up the rock forming mineralsminerals
Oxygen (O) Oxygen (O) 45.20%45.20%Silicon (Si) Silicon (Si) 27.20%27.20%Aluminum (Al)Aluminum (Al) 8.00% 8.00%Iron (Fe)Iron (Fe) 5.80% 5.80%Calcium (Ca)Calcium (Ca) 5.06% 5.06%Magnesium (Mg)Magnesium (Mg) 2.77% 2.77%Sodium (Na)Sodium (Na) 2.32% 2.32%Potassium (K)Potassium (K) 1.68% 1.68%
OtherOther > 1% > 1% Ti, H, Mn, PTi, H, Mn, P
Mineral FamiliesMineral Families• Scientists have identified approx. 4,000 minerals.Scientists have identified approx. 4,000 minerals.• What’s in a rock? – common elements that make upWhat’s in a rock? – common elements that make up rocksrocks
Minerals of the Earth’s CrustMinerals of the Earth’s CrustMinerals are separated into mineral Minerals are separated into mineral
classes.classes. based on the anion complexbased on the anion complex metal (Cation) + non-metal (Anion)metal (Cation) + non-metal (Anion) Example: NaClExample: NaCl
The Mineral Groups according to the The Mineral Groups according to the anionanionOxides (0)Oxides (0) Sulfides (S)Sulfides (S) Sulfates (S0Sulfates (S044))Native ElementsNative Elements Halides (Group 17)Halides (Group 17) Carbonates (C0Carbonates (C033))Silicates (Si0Silicates (Si044))
CationCation AnionAnion
What two elements combined would produce the What two elements combined would produce the mostmost
abundant mineral group?abundant mineral group?Si and 0Si and 0Silicon and Oxygen combined make the Silicon and Oxygen combined make the Silicate mineral Silicate mineral group.group.
•Largest mineral groupLargest mineral group•Si + 0 = (Si + 0 = (Si0Si044))4-4- •Forms the Si0Forms the Si044 Tetrahedron Tetrahedron
• covalently bondedcovalently bonded•4 oxygens with 1 silicon4 oxygens with 1 silicon•building block for all silicate mineralsbuilding block for all silicate minerals•very strong bond – hard to breakvery strong bond – hard to break•(Si0(Si044))-4-4 unstable, wants to combine with unstable, wants to combine with metalsmetals“triangles” put together – very stable
makes tough, hard minerals
I I Earth Science better the thirdEarth Science better the third week. week.
I will get an A on my exams and quizzes.I will get an A on my exams and quizzes.
Discuss with a friend:Discuss with a friend: 13. How are minerals grouped? Name13. How are minerals grouped? Name at least four groups.at least four groups.14. Name the two most common elements14. Name the two most common elements comprising the rock forming minerals.comprising the rock forming minerals.15. Describe the characteristics of the silicate15. Describe the characteristics of the silicate tetrahedron.tetrahedron.16. Why is the tetrahedron so strong?16. Why is the tetrahedron so strong?
How the silicate tetrahedrons bond:How the silicate tetrahedrons bond:• silicate tetrahedron configurations are a function of temp.silicate tetrahedron configurations are a function of temp.• bonding of most silicates is a combination of bonding of most silicates is a combination of covalent and ionic bondscovalent and ionic bondsHotHot
CoolCool
Single tetrahedronSingle tetrahedronMgMg22SiOSiO44
OlivineOlivine
Silicate Silicate tetrahedrontetrahedron
Hexagonal ringHexagonal ringBeBe33AlAl22SiSi66OO1818BerylBeryl
Single chainSingle chainCa Mg (SiOCa Mg (SiO33))22PyroxenePyroxene
groupgroup Double chainDouble chainCaCa22MgMg55(Si(Si44OO1111))22(OH)(OH)22
AmphiboleAmphibolegroupgroup
MicaMicagroupgroup
SheetSheetK(MgFe)K(MgFe)33(AlSi(AlSi33OO1010)(OH))(OH)22
FrameworkFrameworktetrahedrontetrahedron
SiOSiO22