Presentation on theme: "Building Blocks of Rocks"— Presentation transcript:
1Building Blocks of Rocks MineralsBuilding Blocks of Rocks
2What makes minerals and rocks ? ElementsMineralsRocksFe, Mg, Si, O, Kchemical compoundsigneous, sedimentary, metamorphicsilicon (Si)quartzgraniteoxygen (O)sandstoneorthoclaseiron (Fe)gneissbiotite
3The basic atom model (inside the atom) ProtonsNeutronsElectronse+NAtomic numbernumber of protonsdetermines chemicalcharacteristicsrange from 1 (H) to92 (Ur)electron shellseNN+NeeNeeAtomic massprotons + neutronsneutrons add “atomicweight”same atom can havevarying number ofneutrons-- isotopesNNnucleuse
5Elements and the Periodic Table (PT) ELEMENTS Considered a pure substanceeach element has its own atomic numberAbout 118 known elements (92 natural, 26 synthetic)Elements possess distinctive physical propertieshardness, boiling pointssolid, liquid, or gas
6METALS Non-metals 7 increasing atomic numbers Metalloids Periods Groupssimilarproperties7
7Au Gold Interpreting the PT- 79 197.0 Atomic number number of protons Elemental symbolAtomic weightprotons + neutrons197.0GoldElement nameSo, observing the PT patterns and the definition of an element,what characteristics distinguish one element from another?Why is an element considered a pure substance????
8I Earth Science better the second week. Discuss with a friend: ICDiscuss with a friend:What are the parts of an atom? – bespecific (sub-atomic parts).2. How would you describe a chemicalelement?3. What distinguishes one element fromanother?I will get an A on my exams and quizzes.
9P Bonding the atoms (elements) Atoms bond using electrons found at the most outer electron energy shell (valence shell)Electrons enter higher shell levels afterlower shell levels have been filled.Electrons will either be shared ortransferred to other atoms at the valence shell.Valence shelleThe atom wants to be satisfied or stableby filling the electron shells to capacity.Electrons are lost OR gained whensatisfying the outer shell (valence shell).eeePIons – the net electric charge of the atomloses an electron (positive charge)gains an electron (negative charge)equal number of electrons/protons(electrically balanced – neutral)Cation (+ ions), Anions (-) ionseeeeeee
10Na Cl + NaCl Combining Elements (Atoms) to Make Minerals Example: Elements are bonded through “electrical glue” using electronsfrom various element configurations that form chemicalcompounds. Compounds display completely different physicalproperties.Example:+NaClNaClsodium (Na)metallicsoftexplosivelethal!chlorine (Cl)yellow gaslethal!halitenew propertiescompoundcan eat itwe need it
11Ionic bonding Covalent bonding Metallic bonding Van der Waals bonding Bonding the elements – the force that holds theatoms together in a chemical compoundTypes of bonding (atomic bonds)Ionic bondingCovalent bondingMetallic bondingVan der Waals bonding
12+ NaCl = The Ionic Bond – electrically transferred electrons 1 = valence shell7 = valence shelleeeClNaClNa+=eeeeeSodium ion wants tolose the electron(+) positive charge ionChlorine ion wants togain the electron(-) charged ionThe Ionic Bondmoderate strength and hardnessweak bond (salt dissolves in water)Mineral exampleshalite (table salt)biotite
13Loses electrons at the valence shell (+) charged ions Gain or shareelectrons atthe valence shellNaCl = Halite (Salt)(-) charged ions
14The Covalent Bond – sharing electrons The Diamond“perfect geometry”eeeecceeeeeeceeceeeeeeeecceeeeThe Covalent Bondthe strongest bondmost minerals will scratch glassextremely hard to break the bonds
15Metallic bonding – tightly packed atoms “stick” to each other (a form of sharing). Outermost electrons(loosely held) freely move from one atom to the next.good conductors of heat andelectricityheavy “dense”malleable (metals bend easily)polish easilyExamples of metallic minerals:galena (PbS)pyrite (Fe2S)gold (Au)
16Van der Waals bonding – weak attraction between electrically neutral molecules; (+) end of the moleculeis attracted to the (-) end of the molecule.Graphite exampleCarbonatomsvery weak bondseasily broken“layers” slip past oneanotherVan derWaals bondsCovalentbondsSo, why do graphite and diamond displaydifferent physical properties (hardness???)—They are both composed of carbon.18
17I Earth Science. Discuss with a friend: 4. What part of the atom bonds togetherto form compounds?5. Explain the differences between ionic,covalent, metallic, and Van derWaals bonds.I will get an A on my exams and quizzes.
18What are Minerals? What objects below do you think are minerals?? Gold WaterGasolineWoodDiamond
19Why are gold, pyrite, and diamond considered minerals? The 5-part mineral definition:Naturally occurringInorganic (non-living)Homogeneous – solidDefinite chemical compositionDefinite crystalline internal structure4,000 different minerals (fits 5-part definition)25 common minerals combined to form rocks
20I Earth Science. Discuss with a friend: 6. What is the “5-part definition” of amineral?7. Name 3 substances that are NOTminerals and 3 substances that areminerals.8. Is ice a mineral? Is water a mineral?why or why not?I will get an A on my exams and quizzes.
21What’s inside a mineral A mineral’s crystalline structure (internal geometric shape) is the result of the atomic arrangement of atoms (how the atoms align).Dependent on:the size of various combining ionshow the ions bond togetherCl (Chlorine atom)Na (Sodium atom)
22Pyrite Fe2S Quartz SiO2 Do ALL minerals “grow” and show the observer their crystalline shape? (how the atoms combine)PyriteFe2SQuartzSiO2
23Time to GROW Enough SPACE Enough MATERIALS Why do some minerals show theirinternal structure to the observer?Time to GROWEnough SPACEEnough MATERIALS
25Crystal faces – any solid body that has grown with flat “planar” surfaces called crystal facesThe same mineral may grow in a large, small,or skinny form, but the ANGLE between crystal faceswill always remain the same.reflects the internal atomic arrangement of atomsproved by Danish physician- Nicolaus Steno, 1669Steno’s Law states:The angle between any correspondingpairs of crystal faces of a given mineral isconstant no matter what the overall shapeor size of the crystal might be.
26Examples of atom by atom crystal growth exhibiting various angles fat, skinny, tall, short, etc… all the same angles
27The atomic arrangement of atoms in a liquid there is none atoms are randomly arrangedan amorphous solida “liquid-type” solid possessing no internalstructureamorphous material has no melting pointExample:glass, plastic, waxamorphousstructureWaxesGlassPlasticcrystallinestructure
28I Earth Science better the second week. Discuss with a friend: ICDiscuss with a friend:9. What dictates a mineral’s crystallinestructure?10. What conditions must be met to formperfect crystal faces?11. Do all minerals show their crystallinestructure to the observer (why/why not)?12. Describe the differences betweenamorphous and crystalline structures.
29Mineral Families Scientists have identified approx. 4,000 minerals. What’s in a rock? – common elements that make uprocks8 elements make up the rock forming mineralsOxygen (O) %Silicon (Si) %Aluminum (Al) %Iron (Fe) %Calcium (Ca) %Magnesium (Mg) %Sodium (Na) %Potassium (K) %Other > 1%Ti, H, Mn, P
30Minerals are separated into mineral classes. Minerals of the Earth’s CrustMinerals are separated into mineral classes.based on the anion complexmetal (Cation) + non-metal (Anion)Example: NaClCationAnionThe Mineral Groups according to the anionOxides (0) Sulfides (S) Sulfates (S04)Native Elements Halides (Group 17) Carbonates (C03)Silicates (Si04)
31“triangles” put together – very stable makes tough, hard minerals What two elements combined would produce the mostabundant mineral group?Si and 0Silicon and Oxygen combined make the Silicate mineral group.Largest mineral groupSi + 0 = (Si04)4-Forms the Si04 Tetrahedroncovalently bonded4 oxygens with 1 siliconbuilding block for all silicate mineralsvery strong bond – hard to break(Si04)-4 unstable, wants to combine with metals“triangles” put together – very stablemakes tough, hard minerals
32I Earth Science better the third week. Discuss with a friend: 13. How are minerals grouped? Nameat least four groups.14. Name the two most common elementscomprising the rock forming minerals.15. Describe the characteristics of the silicatetetrahedron.16. Why is the tetrahedron so strong?I will get an A on my exams and quizzes.
33How the silicate tetrahedrons bond: silicate tetrahedron configurations are a function of temp.bonding of most silicates is a combination ofcovalent and ionic bondsSilicatetetrahedronHotSingle tetrahedronMg2SiO4OlivineHexagonal ringBe3Al2Si6O18BerylSingle chainCa Mg (SiO3)2PyroxenegroupDouble chainCa2Mg5(Si4O11)2(OH)2AmphibolegroupSheetK(MgFe)3(AlSi3O10)(OH)2MicagroupSiO2FrameworktetrahedronCool