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Minerals Building Blocks of Rocks Minerals Building Blocks of Rocks.

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Presentation on theme: "Minerals Building Blocks of Rocks Minerals Building Blocks of Rocks."— Presentation transcript:

1 Minerals Building Blocks of Rocks Minerals Building Blocks of Rocks

2 What makes minerals and rocks ? Fe, Mg, Si, O, K chemical compounds igneous, sedimentary, metamorphic silicon (Si) oxygen (O) iron (Fe) quartz orthoclase biotite granite sandstone gneiss ElementsMinerals Rocks

3 The basic atom model (inside the atom)ProtonsElectronsNeutrons N N N N N N N e ee e e ee electron shells Atomic number Atomic number number of protons number of protons determines chemical determines chemical characteristics characteristics range from 1 (H) to range from 1 (H) to 92 (Ur) 92 (Ur) Atomic mass protons + neutrons protons + neutrons neutrons add “atomic neutrons add “atomic weight” weight” same atom can have same atom can have varying number of varying number of neutrons-- isotopes neutrons-- isotopes nucleus

4 Germanium atoms (Gr) cobalt (Co) atoms bonding with copper (Cu) atoms cobalt (Co) atoms bonding with copper (Cu) atoms silicon + oxygen (silicate tetrahedron) silicon + oxygen (silicate tetrahedron) Oxygen (4) Silicon (1)

5 Elements and the Periodic Table (PT) ELEMENTS Considered a pure substance Considered a pure substance each element has its own atomic number each 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 properties Elements possess distinctive physical properties hardness, boiling points hardness, boiling points solid, liquid, or gas solid, liquid, or gas

6 increasing atomic numbers Groups similar properties Periods Non-metals Metalloids 7

7 Interpreting the PT- Interpreting the PT- 79 Au Gold Atomic number number of protons number of protons Elemental symbol Atomic weight protons + neutrons protons + neutrons Element name So, 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????

8 II Earth Science better the second week. I will get an A on my exams and quizzes. Discuss with a friend: 1.What are the parts of an atom? – be specific (sub-atomic parts). specific (sub-atomic parts). 2. How would you describe a chemical element? element? 3. What distinguishes one element from another? another? IC

9 Bonding the atoms (elements) Atoms bond using electrons found at the most outer electron energy shell (valence shell) Atoms bond using electrons found at the most outer electron energy shell (valence shell) P ee e e e e ee e e e Valence shell Electrons enter higher shell levels after lower shell levels have been filled. Electrons will either be shared or transferred to other atoms at the valence shell. The atom wants to be satisfied or stable by filling the electron shells to capacity. Electrons are lost OR gained when satisfying the outer shell (valence shell). Ions – the 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/protons equal number of electrons/protons (electrically balanced – neutral) (electrically balanced – neutral) Cation (+ ions), Anions (-) ions Cation (+ ions), Anions (-) ions

10 Combining Elements (Atoms) to Make Minerals Elements are bonded through “electrical glue” using electrons from various element configurations that form chemical compounds. Compounds display completely different physical properties. Example: + NaClNaCl sodium (Na) sodium (Na) metallic metallic soft soft explosive explosive lethal! lethal! chlorine (Cl) chlorine (Cl) yellow gas yellow gas lethal! lethal! halite halite new properties new properties compound compound can eat it can eat it we need it we need it

11 Bonding the elements – the force that holds the atoms together in a chemical compound Types of bonding (atomic bonds) Ionic bonding Ionic bonding Covalent bonding Covalent bonding Metallic bonding Metallic bonding Van der Waals bonding Van der Waals bonding

12 The Ionic Bond – electrically transferred electrons + Na e = NaCl Sodium ion wants to lose the electron (+) positive charge ion (+) positive charge ion Chlorine ion wants to gain the electron (-) charged ion ee e e ee Cl e e The Ionic Bond moderate strength and hardness moderate strength and hardness weak bond (salt dissolves in water) weak bond (salt dissolves in water) 1 = valence shell 7 = valence shell Mineral examples halite (table salt) halite (table salt) biotite biotite

13 Gain or share electrons at the valence shell NaCl = Halite (Salt) Loses electrons at the valence shell (+) charged ions (-) charged ions

14 The Covalent Bond – sharing electrons ee ee eeee cc ee ee ee ee cc ee ee eeee cc ee ee eeee cc eeee eeee cc ee ee eeee cc The Diamond “perfect geometry” The 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 The 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

15 Metallic 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 and electricity electricity heavy “dense” heavy “dense” malleable (metals bend easily) malleable (metals bend easily) polish easily polish easily Examples of metallic minerals: galena (PbS) pyrite (Fe 2 S) gold (Au)

16 Van der Waals bonding – weak attraction between electrically neutral molecules; (+) end of the molecule is attracted to the (-) end of the molecule. Carbon atoms Covalent bonds Van der Waals bonds very weak bonds easily broken easily broken “layers” slip past one “layers” slip past one another another Graphite example So, why do graphite and diamond display different physical properties (hardness???)— They are both composed of carbon. 18

17 II Earth Science. I will get an A on my exams and quizzes. Discuss with a friend: 4. What part of the atom bonds together to form compounds? to form compounds? 5. Explain the differences between ionic, covalent, metallic, and Van der covalent, metallic, and Van der Waals bonds. Waals bonds.

18 What objects below do you think are minerals?? What objects below do you think are minerals?? Gold Gasoline Diamond Water Wood What are Minerals?

19 Why are gold, pyrite, and diamond considered minerals? Why are gold, pyrite, and diamond considered minerals? The 5-part mineral definition: The 5-part mineral definition: Naturally occurring Inorganic (non-living) Inorganic (non-living) Homogeneous – solid Homogeneous – solid Definite chemical composition Definite chemical composition Definite crystalline internal structure Definite crystalline internal structure 4,000 different minerals (fits 5-part definition) 4,000 different minerals (fits 5-part definition) 25 common minerals combined to form rocks 25 common minerals combined to form rocks

20 II Earth Science. I will get an A on my exams and quizzes. Discuss with a friend: 6. What is the “5-part definition” of a mineral? mineral? 7. Name 3 substances that are NOT minerals and 3 substances that are minerals and 3 substances that are minerals. minerals. 8. Is ice a mineral? Is water a mineral? why or why not? why or why not?

21 What’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). What’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). Cl (Chlorine atom) Na (Sodium atom) Dependent on: the size of various combining ions the size of various combining ions how the ions bond together how the ions bond together

22 Do ALL minerals “grow” and show the observer their crystalline shape? (how the atoms combine) Do ALL minerals “grow” and show the observer their crystalline shape? (how the atoms combine) Fe 2 S Pyrite Quartz SiO 2

23 Why do some minerals show their internal structure to the observer? Why do some minerals show their internal structure to the observer?

24 large gypsum crystals formed 150 feet below the surface large gypsum crystals formed 150 feet below the surface Enough space Enough time Enough solution Enough space Enough time Enough solution Chihuahua Desert, Mexico

25 Crystal faces – any solid body that has grown with flat “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 ANGLE between crystal faces or skinny form, but the ANGLE between crystal faces will always remain the same. will always remain the same. reflects the internal atomic arrangement of atoms reflects the internal atomic arrangement of atoms proved by Danish physician- Nicolaus Steno, 1669 proved by Danish physician- Nicolaus Steno, 1669 Steno’s Law states: Steno’s Law states: The angle between any corresponding pairs of crystal faces of a given mineral is pairs of crystal faces of a given mineral is constant no matter what the overall shape constant no matter what the overall shape or size of the crystal might be. or size of the crystal might be.

26 Examples of atom by atom crystal growth exhibiting various angles fat, skinny, tall, short, etc… all the same angles

27 The atomic arrangement of atoms in a liquid there is none there is none atoms are randomly arranged atoms are randomly arranged an amorphous solid an amorphous solid a “liquid-type” solid possessing no internal a “liquid-type” solid possessing no internal structure structure amorphous material has no melting point amorphous material has no melting point Example: Example: glass, plastic, wax glass, plastic, waxamorphousstructure crystallinestructure Waxes Glass Plastic

28 II Earth Science better the second week. Discuss with a friend: 9. What dictates a mineral’s crystalline structure? structure? 10. What conditions must be met to form perfect crystal faces? perfect crystal faces? 11. 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 amorphous and crystalline structures. amorphous and crystalline structures. IC

29 8 elements make up the rock forming minerals Oxygen (O) 45.20% Silicon (Si) 27.20% Aluminum (Al) 8.00% Iron (Fe) 5.80% Calcium (Ca) 5.06% Magnesium (Mg) 2.77% Sodium (Na) 2.32% Potassium (K) 1.68% Other > 1% Other > 1% Ti, H, Mn, P Ti, H, Mn, P Mineral Families Scientists have identified approx. 4,000 minerals. What’s in a rock? – common elements that make up What’s in a rock? – common elements that make up rocks rocks

30 Minerals of the Earth’s Crust Minerals are separated into mineral classes. based on the anion complex based on the anion complex metal (Cation) + non-metal (Anion) metal (Cation) + non-metal (Anion) Example: NaCl Example: NaCl The Mineral Groups according to the anion Oxides (0)Sulfides (S)Sulfates (S0 4 ) Native ElementsHalides (Group 17)Carbonates (C0 3 ) Silicates (Si0 4 ) CationAnion

31 What two elements combined would produce the most abundant mineral group? Si and 0 Silicon and Oxygen combined make the Silicate mineral group. Largest mineral groupLargest mineral group Si + 0 = (Si0 4 ) 4-Si + 0 = (Si0 4 ) 4- Forms the Si0 4 TetrahedronForms the Si0 4 Tetrahedron covalently bonded covalently 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 4 ) -4 unstable, wants to combine with metals(Si0 4 ) -4 unstable, wants to combine with metals “triangles” put together – very stable makes tough, hard minerals

32 II Earth Science better the third week. I will get an A on my exams and quizzes. Discuss with a friend: 13. How are minerals grouped? Name 13. How are minerals grouped? Name at least four groups. at least four groups. 14. Name the two most common elements comprising the rock forming minerals. comprising the rock forming minerals. 15. Describe the characteristics of the silicate tetrahedron. tetrahedron. 16. Why is the tetrahedron so strong?

33 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 bonds covalent and ionic bondsHot Cool Single tetrahedron Mg 2 SiO 4 Olivine Silicatetetrahedron Hexagonal ring Be 3 Al 2 Si 6 O 18 Beryl Single chain Ca Mg (SiO 3 ) 2 Pyroxenegroup Double chain Ca 2 Mg 5 (Si 4 O 11 ) 2 (OH) 2 Amphibolegroup Micagroup Sheet K(MgFe) 3 (AlSi 3 O 10 )(OH) 2 Frameworktetrahedron SiO 2


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