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CHEM 163 Chapter 22

CHEM 163 Chapter 22. Spring 2009. The Elements in Nature. What is the earth?. 4.5 billion year old planet. Differentiation : regions of differing composition and density. Core: 10-15 g/cm 3 Molten outer core Solid inner core Mantle: 4-6 g/cm 3 Crust: 2.8 g/cm 3.

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CHEM 163 Chapter 22

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  1. CHEM 163Chapter 22 Spring 2009

  2. The Elements in Nature What is the earth? 4.5 billion year old planet Differentiation: regions of differing composition and density • Core: • 10-15 g/cm3 • Molten outer core • Solid inner core • Mantle: • 4-6 g/cm3 • Crust: • 2.8 g/cm3

  3. Abundances of Elements • Large differences between Earth & universe (especially for H) • O, Si, Fe, Mg abundant in Earth & universe • 90% of Earth’s mass • Core rich in Co, Ni, Fe (dense metals); no O • Crust is unique • Nonmetals; metalloids; light, active metals (Al, Ca, Na, K)

  4. Making of the Earth • Cold gases + debris from former stars = Sun + planets • Cold, uniform solid sphere • Heats up to 104 K  molten earth • Radioactive decay • Lots of meteor impacts • Earth cooled  layered earth • Dense material sinks • Fe • Lighter material rises • Silicates: Si, Al, Mg (some Fe) + oxygen (rocks) • Gases form atmosphere • H2O, CO, N2 or NH3 core mantle crust

  5. Earth’s Crust • Solid, liquid and gas • Lithosphere • Hydrosphere • Atmosphere • Biosphere: living systems that have inhabited the planet • Energy for reactions: • Geothermal; lightning; solar; meteors • Simple algae: CO2 + H2O  organic molecules + O2 • Oxidation http://stloe.most.go.th/html/lo_index/LOcanada1/102/images/L02_4.jpg

  6. Life’s Effect On Earth • Created oxidizing environment • Distributed elements • [Na+] >>> [K+] in oceans • K+ part of clay • K+ absorbed by plants • TM oxides and sulfides (insoluble)

  7. Sources of Elements In what form is each element found? • Pure (diatomics; Au, Pt; C in coal) • Oxides • Salts ore: natural compound or mixtures of compounds from which elements can be harvested ($)

  8. The Elements in Nature & Industry • Teaching in pairs Wednesday: • Fuel Cells (21.5)—Chris & Taylor • The Carbon Cycle & the Nitrogen Cycle (22.2) – Jarrett & Ani • The Phosphorous Cycle (22.2) – Darby & Toan • Metallurgy: Extracting a Metal From its Ore (22.3) – Hana & Terri Thursday: • Na & K Metals; Magnesium & Bromine (22.4) – Tae & Zephan • Iron, Copper, and Aluminum (22.4) – Nicole & Liz • The Many Sources & Uses of Hydrogen (22.4) – Jena & Trung • Chemical Manufacturing (22.5) – Brenna & Robert • Homework (due Tues. 6/9) • Quiz (Thursday, 6/11)

  9. Requirements • 8-10 minute presentation • 1-2 minutes for questions • Cover the main points from your section • Both group members must speak • Reference any sources of information used • An original visual aid must be created and used as part of your presentation • Poster, PowerPoint presentation, brochure, other • Both presentation and visual aid must be clearly organized

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