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I. Metallic Bonds

I. Metallic Bonds. How atoms are held together in the solid form. Metals hold onto their valence electrons very weakly. Think of them as positive ions floating in a sea of electrons. http://www.youtube.com/watch?v=c4udBSZfLHY https:// www.youtube.com/watch?v=D1mLBIjBdSg. +. +. +. +. +.

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I. Metallic Bonds

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  1. I. Metallic Bonds • How atoms are held together in the solid form. • Metals hold onto their valence electrons very weakly. • Think of them as positive ions floating in a sea of electrons.

  2. http://www.youtube.com/watch?v=c4udBSZfLHY • https://www.youtube.com/watch?v=D1mLBIjBdSg

  3. + + + + + + + + + + + + Sea of Electrons • Electrons are free to move through the solid. • Metals conduct electricity.

  4. Metals are Malleable • Hammered into shape (bend). • Ductile - drawn into wires.

  5. + + + + + + + + + + + + Malleable

  6. + + + + + + + + + + + + Malleable • Electrons allow atoms to slide by.

  7. ALLOYS • Alloys are solid solutions made by dissolving metals in other metals. They are prepared by melting the metals together and cooling the mixture. • The properties of alloys differ from those of their component metals. For example stainless steel, an alloy of iron, carbon, chromium and nickel is stronger than iron and more resistant to corrosion.

  8. Name of Alloy Composition ________________________________________ Sterling silver silver, copper Brass copper, zinc, tin Cast iron iron, carbon Steel iron, carbon Stainless steel iron, chromium, carbon, nickle 18 Carat gold gold, silver, copper Pewter tin, copper, bismuth, antimony Plumber’s solder lead, tin

  9. ALLOY • A combination of 2 metals

  10. Metallic Bonds – Properties of Metals • Metallic Bonds 1. valence electrons are delocalized a. free to move from atom to atom 2. bond is formed by the attraction of metal cations for the moving electrons 3. “electron sea model” –atoms of metals contribute a “sea” of free moving electrons that move from one atom to another

  11. Electron Sea Model for Metallic Bonds

  12. Positive Ions Surrounded by Delocalized Electrons

  13. Properties of Metals 1. moderately high melting points 2. high boiling points 3. malleable a. can be hammered into sheets 4. ductile a. can be drawn into wire 5. good conductors of heat and electricity 6. luster(good reflectors of light) 7. hardness and strength varies a. greater in transition elements

  14. C. Alloys 1. mixture of two or more elements with metallic properties 2. types a. substitutional– atoms of similar size (sterling silver, brass, pewter) b. interstitial – small holes in the crystal filled with smaller atoms (carbon steel)

  15. review lab concepts • http://bcs.whfreeman.com/chemcom6e/#665402__741664__

  16. Video • Review the information • http://www.youtube.com/watch?v=Bjf9gMDP47s

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