planet earth minerals_powerpoint_presentation

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  • 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.

2. Summary of Important Concepts to Be Covered

  • The Earth consists of four interconnected systems: thesolid earth or lithosphere(rock and soil); theatmosphere ; thehydrosphere ; thebiosphere ; These systems interact and influence each other.
  • 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.

3. Summary of Important Concepts to Be Covered

  • Rocksare composed on one or more minerals. There are three main classes of rocks:
    • Igneous rocksform from solidification of magma (molten rock)
    • Sedimentary rocksform from solidification of sediment (particles formed from the erosion of older rocks, or by chemical or biological processes at the earths surface).
    • Metamorphic rocksform from other rocks changed by heat and pressure
  • One type of rock can be transformed into another type over geologic time; aprocess known as therock cycle .

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

  • Knowing the chemistry is essential to knowing how they combine to form rocks and the stability of the rocks.
  • Uses: natural resources, nutrients, metals, building materials, jewelry, computer chips.
  • ~4000 species of mineral but only about 20 or so are actually common.

6. Definition of a Mineral

  • Naturally occurring (not synthesized by man).
  • Inorganic (not made from living organisms).
  • Solid that is homogenous (the same throughout).
  • Ordered crystalline structure (atoms are arranged in a definite pattern that repeats throughout the entire mineral).
  • Definite chemical composition expressed with a formula.

Halite or common table salt NaCl 7. Atoms, atoms, atoms!

  • An element is electrically neutral.
  • ~92 naturally occurring, ~17 man made
  • 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).

8. Periodic Table of the Elements http://www.chemicalelements.com 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

  • Atomic number = # of protons (+).Determines the element.
  • Atomic mass= # protons and neutrons in nucleus.
  • Neutrons, no charge, contributes to atomic mass.
  • Electrons (-), doesnt contribute to mass.
  • All atoms are electrically neutral. That means the number of protons (+) in the nucleus eguals the number of electrons orbiting the nucleus .

12. Electrons

  • Negatively charged sub-atomic particles that move very quickly around the nucleus.
  • 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.
  • 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).
  • For an atom to be STABLE, that is, not bond or chemically react with another atom, its VALENCE shell (outermost shell) must be full.
  • Electrons and valence shells are involved in chemical BONDING.

13. Chemical bonding between elements forms minerals. Covalent and Ionic Bonds 14. TO BOND OR NOT TO BOND

  • If the number of protons equals the number of electrons (+ = -) and the checkbook balances the atom has no charge.
  • Having no charge does not necessarily mean the atom is stable.
  • Take Na (sodium).Check the periodic table to get its atomic number (the number of protons, that is).

15. TO BOND OR NOT TO BOND

  • Na atomic number is 11.
  • How many electrons in the valence shell?
  • One valence electron.Well to be stable and non reactive, we want to have a full valence shell.
  • Na can accept 7 electrons or give up 1.Which seems easier?

16. TO BOND OR NOT TO BOND

  • Sure!It is much easier to donate that one electron so that the shell is full.
  • What is the charge on sodium if it gives up that electron?
  • +1It has a plus one charge and is now called an ION, specifically a cation (positively charged ion).
  • Diagram shows sodium atom on the left and the ion on the right.Sorry, its in french.
  • If an element gives away two electrons it will have a +2 charge and so forth and so on.

17. TO BOND OR NOT TO BOND

  • Now go look up the atomic number for Chlorine Cl. How about the valence shell?
  • You should come up with 7 valence electrons.What a dilemma.Cl only needs ONE more electron to have a full valence shell.
  • If Cl obtains one electron it will have 17 protons, 18 electrons and a charge of -1.An anion is a negatively charged ion.
  • Now we have an electric glue.Opposites attract right?Well, Na+1 and Cl-1 will have to form a bond.

18. Ionic Bonds

  • 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).

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

  • 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.
  • 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.
  • The number of covalent bonds an atom can have depends on the number of valence electrons.

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

  • 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).
  • Si (silicon)
  • O (oxygen) Si and O form the silica tetrahedron
  • Na (sodium) +1
  • K (potassium) +1
  • Ca (calcium) +2
  • Mg (magnesium) +2
  • Al (aluminum) +3
  • Fe (iron) +2
  • 98% of the earths crust are made of combinations of these 8 elements.
  • 92% of the earths crust are made of silicate minerals, those containing mostly Si and O.

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

  • The fundamental building block for the silicate minerals is called the silica tetrahedron.Stats on Si and O are as fo