Planet earth minerals_powerpoint_presentation

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<ul><li> 1. Matter and Minerals The spectacular scenery of the Sierra Nevada Mountains in California results from glaciers that carved high peaks and deep valleys into a massive body ofgranite-- a common type ofigneous rock . Igneous rocks are rocks that form the cooling and solidification of molten magma.</li></ul><p> 2. Summary of Important Concepts to Be Covered </p> <ul><li>The Earth consists of four interconnected systems: thesolid earth or lithosphere(rock and soil); theatmosphere ; thehydrosphere ; thebiosphere ; These systems interact and influence each other. </li></ul><ul><li>The earthscrustconsists of rocks made of various types of minerals.Mineralsare classified into different groups according to their chemistry. Thesilicatemineral group makes up most rock of the crust. </li></ul><p> 3. Summary of Important Concepts to Be Covered </p> <ul><li>Rocksare composed on one or more minerals. There are three main classes of rocks:</li></ul><ul><li><ul><li>Igneous rocksform from solidification of magma (molten rock) </li></ul></li></ul><ul><li><ul><li>Sedimentary rocksform from solidification of sediment (particles formed from the erosion of older rocks, or by chemical or biological processes at the earths surface). </li></ul></li></ul><ul><li><ul><li>Metamorphic rocksform from other rocks changed by heat and pressure </li></ul></li></ul><ul><li>One type of rock can be transformed into another type over geologic time; aprocess known as therock cycle . </li></ul><p> 4. The earths crust is made of various kinds ofrock , and rock is composed of one or moreminerals . For example, as this picture shows, the rockgraniteis composed mostly of the mineralsquartz, biotite,andfeldspar. 5. Importance of Minerals </p> <ul><li>Knowing the chemistry is essential to knowing how they combine to form rocks and the stability of the rocks. </li></ul><ul><li>Uses: natural resources, nutrients, metals, building materials, jewelry, computer chips. </li></ul><ul><li>~4000 species of mineral but only about 20 or so are actually common. </li></ul><p> 6. Definition of a Mineral </p> <ul><li>Naturally occurring (not synthesized by man). </li></ul><ul><li>Inorganic (not made from living organisms). </li></ul><ul><li>Solid that is homogenous (the same throughout). </li></ul><ul><li>Ordered crystalline structure (atoms are arranged in a definite pattern that repeats throughout the entire mineral). </li></ul><ul><li>Definite chemical composition expressed with a formula. </li></ul><p>Halite or common table salt NaCl 7. Atoms, atoms, atoms! </p> <ul><li>An element is electrically neutral.</li></ul><ul><li>~92 naturally occurring, ~17 man made </li></ul><ul><li>Smallest unit of matter that cannot be broken down into other substances (i.e. its the smallest part of the element that retains the properties of that element). </li></ul><p> 8. Periodic Table of the Elements 9. Minerals are made of various chemicalelements , oratoms .Atoms, which form all matter, consist of three kinds of particles. --protonswith a positive charge andneutronswith a neutral charge -- occupy the center, ornucleus , of the atom. The nucleus contains nearly all themassof the atom.--electronswith a negative charge -- orbit around the nucleus. Electrons have almost zero mass.All atoms have this same general structure .By changing thenumbersof protons we makedifferent chemical elements ! 10. Periodic Table of the Elements 11. Anatomy of an Atom </p> <ul><li>Atomic number = # of protons (+).Determines the element. </li></ul><ul><li>Atomic mass= # protons and neutrons in nucleus. </li></ul><ul><li>Neutrons, no charge, contributes to atomic mass. </li></ul><ul><li>Electrons (-), doesnt contribute to mass. </li></ul><ul><li>All atoms are electrically neutral. That means the number of protons (+) in the nucleus eguals the number of electrons orbiting the nucleus . </li></ul><p> 12. Electrons </p> <ul><li>Negatively charged sub-atomic particles that move very quickly around the nucleus. </li></ul><ul><li>Electrons are arranged in shells or orbitals around the nucleus. Electron shells are merely SPACE surrounding the nucleus at different levels.Electrons within a shell can move anywhere within this space. </li></ul><ul><li>The shells are layered where the first shell canonlyhold up to two electrons.Each successive shell can hold up to 8 (as you get up in atomic number, the number or electrons/shell varieswe will not worry about that). </li></ul><ul><li>For an atom to be STABLE, that is, not bond or chemically react with another atom, its VALENCE shell (outermost shell) must be full. </li></ul><ul><li>Electrons and valence shells are involved in chemical BONDING. </li></ul><p> 13. Chemical bonding between elements forms minerals. Covalent and Ionic Bonds 14. TO BOND OR NOT TO BOND </p> <ul><li>If the number of protons equals the number of electrons (+ = -) and the checkbook balances the atom has no charge.</li></ul><ul><li>Having no charge does not necessarily mean the atom is stable. </li></ul><ul><li>Take Na (sodium).Check the periodic table to get its atomic number (the number of protons, that is). </li></ul><p> 15. TO BOND OR NOT TO BOND </p> <ul><li>Na atomic number is 11.</li></ul><ul><li>How many electrons in the valence shell? </li></ul><ul><li>One valence electron.Well to be stable and non reactive, we want to have a full valence shell.</li></ul><ul><li>Na can accept 7 electrons or give up 1.Which seems easier? </li></ul><p> 16. TO BOND OR NOT TO BOND </p> <ul><li>Sure!It is much easier to donate that one electron so that the shell is full. </li></ul><ul><li>What is the charge on sodium if it gives up that electron? </li></ul><ul><li>+1It has a plus one charge and is now called an ION, specifically a cation (positively charged ion).</li></ul><ul><li>Diagram shows sodium atom on the left and the ion on the right.Sorry, its in french. </li></ul><ul><li>If an element gives away two electrons it will have a +2 charge and so forth and so on. </li></ul><p> 17. TO BOND OR NOT TO BOND </p> <ul><li>Now go look up the atomic number for Chlorine Cl. How about the valence shell? </li></ul><ul><li>You should come up with 7 valence electrons.What a dilemma.Cl only needs ONE more electron to have a full valence shell.</li></ul><ul><li>If Cl obtains one electron it will have 17 protons, 18 electrons and a charge of -1.An anion is a negatively charged ion. </li></ul><ul><li>Now we have an electric glue.Opposites attract right?Well, Na+1 and Cl-1 will have to form a bond. </li></ul><p> 18. Ionic Bonds </p> <ul><li>An ionic bond is the chemical bond that results from the electrostatic attraction between positive ions (cations) and negative ions (anions).It can form when two atoms meet and an electron is permanently transferred from one to the other. These two ionized atoms then stick very tightly together to make sodium chloride -- also known as table salt (or the mineral halite). </li></ul><p> 19. So basically electric glue holds NaCl together.This bond is not that strong (as we can dissolve NaCl easily in water). For any element, be able to determine the valence electrons and what charge it would have if it would become an ion. 20. Covalent Bond </p> <ul><li>Okay so what if you have 4 valence electrons.Would you give up or obtain 4 electrons.Probably neither.Your best bet in this situation is to just SHARE the electrons. </li></ul><ul><li>Covalent chemical bonds involve the sharing of a pair of valence electrons by two atoms.A Covalent bond is formed when the valence shells of two atoms overlap and the electrons are free to roam between both shells. </li></ul><ul><li>The number of covalent bonds an atom can have depends on the number of valence electrons. </li></ul><p> 21. Covalent Bonding Note: the more covalent bonding a mineral has in its structure, the more stable (stronger) that mineral is, and the more difficult to weather or break it down. 22. Common Elements of the Earths Crust </p> <ul><li>Okay so if there are thousands of minerals, why only a few common ones?The answer is that there are only a few elements that make up MAJORITY of the earths minerals (and minerals make up rocks).</li></ul><ul><li>Si (silicon) </li></ul><ul><li>O (oxygen) Si and O form the silica tetrahedron </li></ul><ul><li>Na (sodium) +1 </li></ul><ul><li>K (potassium) +1 </li></ul><ul><li>Ca (calcium) +2 </li></ul><ul><li>Mg (magnesium) +2 </li></ul><ul><li>Al (aluminum) +3 </li></ul><ul><li>Fe (iron) +2 </li></ul><ul><li>98% of the earths crust are made of combinations of these 8 elements. </li></ul><ul><li>92% of the earths crust are made of silicate minerals, those containing mostly Si and O. </li></ul><p> 23. For example: Theoxidegroup consists of all minerals formed from various elements bonded to negatively charged oxygen (O-2 ) atoms.Thecarbonategroup consists of all minerals formed from elements bonded to negatively charged carbonate ((CaCO 3)-2) molecules.Thesilicate mineralsare the MOST COMMON minerals in the earths crust. Geologists classify minerals into groups thatshare the same negatively charged atoms or molecules . 24. Silicate Minerals Thesilicatesare the most abundant and important mineral group. Silicates are minerals composed ofsilicate tetrahedra(SiO 4 ) - 4bonded to each other and/or to other elements. A single silicate tetrahedron consists of 1 silicon (Si) atom surrounded by 4 oxygen (O) atoms, forming a tetrahedron shape. These tetrahedra bond readily to each other, and to other elements, forming several kinds of abundant minerals, including quartz and feldspar.feldspar quartz hornblende muscovite mica 25. The Silica Tetrahedron </p> <ul><li>The fundamental building block for the silicate minerals is called the silica tetrahedron.Stats on Si and O are as follows: </li></ul><ul><li>Si atomic number is 14 </li></ul><ul><li>How many valence e-?(4) </li></ul><ul><li>O atomic number is 8</li></ul><ul><li>How many valence e-?(6) </li></ul><ul><li>Silicon therefore can form four covalent bonds with oxygen atoms.</li></ul><p> 26. The Silica Tetrahedron 27. The Silica Tetrahedron 28. The Silica Tetrahedron </p> <ul><li>If each oxygen (four total) share one electron with silicon, then silicons valence shell is full, but what about oxygen? </li></ul><ul><li>No, each oxygen has two vacancies in its valence shell and will require two covalent bonds.So now what? </li></ul><p> 29. The Silica Tetrahedron </p> <ul><li>The chemical formula Si04 will then have a net negative 4 charge.This is because, each of four oxygens have one vacancy in their valence shells.Each Oxygen therefore needs to obtain one more electron to fill its outer shell. </li></ul><ul><li>If the MOLECULE accepts four electrons to become STABLE (and it will), the tetrahedron itself will have obtained four electrons (have full valence shells) and will have an overall charge of -4.</li></ul><p> 30. So where does it get these other 4 electrons?From atoms that want to get rid of their valence electrons (to become cations).Of the remaining abundant elements of the earths crust, you can see that there are many combinations of cations (bottom right) that will form ionic bonds to the tetrahedron and thus form a variety of different minerals.So, eight elements can make many different SILICATE minerals that make up the earths crust. 31. The Silica Tetrahedron 32. The silica tetrahedron itself is covalently (strong) bound, but each tetrahedra is electrically glued to adjacent tetrahedra via the cations.If the silica tetrahedra backbone is arranged in this way, we call this the isolated silicate structure (see next slide). The OTHER way the silica tetrahedra can fill its valence shells is by covalently bonding to adjacent tetrahedra.If it forms two, three, or four covalent bonds (oxygens sharing electrons with oxgyens of adjacent tetrahedra) and subsequent demand for electrons drops, the net negative charge on the tetrahedron becomes less and less. If all four oxygens share electrons, all covalent bonds are formed.There will be no charge (and thus no bonding to cations). 33. The figure shows the shape of the silicate tetrahedron, and shows how progressively more complex bonding between silicate tetrahedra forms the different types of common silicate minerals. 34. Isolated Silicate Minerals </p> <ul><li>Olivine is an example. </li></ul><ul><li>Consists of one tetrahedron bound by 4+ ions.</li></ul><ul><li>It is isolated because it shares no oxygen atoms with other tetrahedra. </li></ul><ul><li>Si:O = 1:4 = +4:-8, net charge = -4 </li></ul><ul><li>-4 binds to +4 cations. </li></ul><ul><li>Because this silicate structure has the highest negative charge, it will form the MOST amount of ionic bonds with adjacent tetrahedra rendering this the WEAKEST silicate structure.</li></ul><ul><li>Olivine contains a lot of Fe and Mg (recall layers of the earth and distribution of Fe, Mg, Si and O). </li></ul><p> 35. Single Chain Silicates </p> <ul><li>Augite is an example. </li></ul><ul><li>Look at the diagram to the left A-single chains. </li></ul><ul><li>View a single blue dot representing the silicon atomeach is surrounded by four beige oxygen atoms. </li></ul><ul><li>Pick out any tetrahedra and see how TWO oxygens are being shared with adjacent tetrahedra. </li></ul><ul><li>Because of some covalent bonding in this backbone the net charge is -2 for this structure. </li></ul><ul><li>Per individual tetrahedra, only two electrons are accepted for the two NON covalently bound oxygens.</li></ul><ul><li>The demand for + ions is less.These minerals have more covalent bonds than the isolated structure and are subsequently stronger. </li></ul><p> 36. Double Chain Silicates </p> <ul><li>Hornblende is an example. </li></ul><ul><li>Examine the B-Double silicate in the figure.Every other tetrahedron shares 3 OR 2 oxygens. </li></ul><ul><li>These silicates have MORE covalent bonds and LESS ionic bonds than the single chains (and so are stronger yet). </li></ul><ul><li>Si:O = 1:2.75 </li></ul><ul><li>+4:-5.5, net charge 1.5 </li></ul><ul><li>Double chains of silicatesare linked together by +1.5 worth of cations. </li></ul><p> 37. Sheet Silicates </p> <ul><li>Muscovite and Biotite as examples. </li></ul><ul><li>Suppose we covalently bind three oxygens with adjacent tetrahedra.The only oxygen that had accepted an electron is the top oxgyen (see diagramit is the one pointed at you). </li></ul><ul><li>The silica is arranged in sheets, and the sheets are electrically glued together by cations.These minerals break easily between the ionic bonds between the sheets. </li></ul><ul><li>Si:O = 1-2.5 </li></ul><ul><li>+4:-5, net charge 1 </li></ul><ul><li>Positive ions IONICALLY bond sheets together. </li></ul><p> 38. Framework Silicates Each tetrahedron shares all four oxygens with adjacent tetrahedra. Si:O = 1:2. All four oxygens shared with adjacent tetrahedron forms a complex 3-D network, all covalently bound. Quartz as an example. Quartz therefore is a pretty stable mineral as it is only SiO2 all covalently bound.The reason that the formula is SiO2 is because each silicon owns half of four oxygens (sharing with other silicon atoms). Quartz (and glass) will not break in a straight line or preferential direction (minerals tend to break along planes of weakness resulting from ionic bonds).Four covalent bonds means strength between the atoms is equal in all directions.Hence, glass (and quartz) breaks in curved patterns (wherever the force was the strongest). 39. High Medium Low Lower Lowest Stability Low Medium High Higher Highest Density Low Medium High Higher Highest Ionic Bonds High Medium Low Lower Lowest Covalent Bonds +4-4=0 +4-5=-1 +4-5.5=-1.5 +4-6=-2 +4-8=-4 Net Charge 1:2 1:2.5 1:2.75 1:3 1:4 Si:O Low Felsic Medium Felsic High Mafic Higher Mafic Highest Ultramafic Percent Fe, Mg High Medium Low Lower Lowest Percent SiO2 Quartz Mica Hornblende Augite Olivine Example Framework Sheet Double Chain Single Chain Isolated Silicate Structure 40. Felsic Silicate Minerals </p> <ul><li>Of the Silicates we can divide them up into smaller groups. </li></ul><ul><li>FELSICsilicate minerals contain high percentages of Si and O and very little Fe and Mg (sometimes none at all). </li></ul><ul><li>Examples include Quartz, Orthoclase Feldspar, Plagioclase Feldspar. </li></ul><ul><li>Felsic minerals tend to be light colored. </li></ul><ul><li>What layer of the earth do you think would be made up of rock composed of felsic minerals? </li></ul><ul><li>Answer:CONTINENTAL CRUST </li></ul><p> 41. Mafic Silicate Minerals </p> <ul><li>Of the silicates, those that have higher percentages of Fe and Mg are calledMAFICminerals. </li></ul><ul><li>They tend to be darker in color. </li></ul><ul><li>Examples include Olivine, Hornblende, Augite, Biotite Mica. </li></ul><ul><li>Mafi...</li></ul>