CH 23: METALS

METALS

Chapter 23

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• Opaque• Good conductors of ______ and __________• High ___________ and __________• Metallic Solids

– Each metal atom releases its _______________to be shared by all the atoms in the crystal.

– Valence electrons occupy an energy band called the ___________that is delocalized over the entire solid.

General Properties and Structure of Metals

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General Properties and Structure of Metals

Conduction Band

Valence Band

Ener

gy

Conductor Semi-conductor Insulator

Small band gap

Large band gap

Having the valence band (continuous area of valence electrons) overlapping with the conduction band (empty area of orbitals) allows metals to conduct electricity when electrons flow from the valence to the conduction band.

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• Semi-Conductors– Small band gap– Often are “doped” with other materials to help

close the band gap• P-type semiconductors—impurity gives material fewer

valence electrons (positively doped)• N-type semiconductors—impurity gives material more

valence electrons (negatively doped)

General Properties and Structure of Metals

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• Metals make up about 25% of Earth’s crust.• Aluminum is the most abundant.• Alkali and alkali earth metals make up about 1%.• Iron is only the transition metal > 5%.• Only Ni, Cu, Ag, Au, Pd, Pt are found in native form.

– Noble metals

• Most metals are found in minerals.– Minerals are natural, homogeneous crystalline

inorganic solids.

Distribution of Metals in Earth

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Mineral Sources of Common Metals

• NaCl = halite; KCl = sylviteBoth recovered from evaporated sea water

• Fe2O3 = hematite; TiO2 = rutile; SnO2 = cassiterite

• PbS = galena; HgS = cinnabar; ZnS = sphalerite; MoS = molybdenite; VS4 = patronite

• [Pb5(VO4)3Cl] = vanadiniteFound mainly at upper levels of galena mines

• [K2(UO2)2(VO4)2 ∙ 3 H2O] = carnotiteFound as crusts or flakes with sandstoneSource of V, U, and Ra (because Ra is found with U)

• [Fe(NbO3)2] = columbite; [Fe(TaO3)2] = tantaliteFound in mixed deposits

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Isolating Metals

• Metallurgy—processes associated with mining separating and refining metals to obtain pure metals– Separations—physical isolation

• Crush metal ores• Gangue is separated out (undesired materials)

– Magnets– Electrostatic forces—polar from nonpolar molecules

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Isolating Metals

– Extractive Metallurgy• Pyrometallurgy—metals exctrated with heat• Hydrometallurgy—extractions with aqueous solutions • Electrometallurgy—extractions using electrolysis• Powder metallurgy—metal powders are compressed to

form desired product

– Refining—crude product purified

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• Alloys are metals that contain more than one type of material.– A base metal and alloying materials

• Alloys show metallic properties.• Most common physical properties of alloys are

often averages of the component metals. • However, engineering properties may be quite

different than the components.– Like tensile strength and shear strength

• Most melt over a large temperature range rather than having a fixed melting point.

Alloys

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• Some alloys are _____________ with variable composition.– ________ = Fe, C, and other metals– ________ = Cu and Zn– ________ = Cu and Sn

• Some have fixed composition like a compound.– ______________________– solids with different crystal

structures than any of their components– ______ − used for its magnetic properties– _____ − memory metal

Alloy Composition

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S-Block Elements

• Properties:– _____________– _________________– Alkali metals react violently with ________

• http://www.youtube.com/watch?v=dmcfsEEogxs

– React with _______________• Trends

– _________ atoms on Periodic Table– Least ______________ and ___________________

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S-block Elements—Flame Tests

Petrucci, et al. General Chemistry.

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S-Block Elements—Uses

• Sodium & Potassium– Na+ is found _____________– K+ is found _____________– _____________________ are used to administer drugs

• ________________is used for manic phases for manic-depressive disorder

• _______________ is used:– As a reducing agent– Fireworks– Batteries

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Hard Water

• Caused by _______________________– _______________________– ______________ hardness: ______ is present– ______________ hardness: any other ions

present• Water softening

– Replaces ___________ with other ions– Uses _____________________

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Water softening

Petrucci, et al. General Chemistry.

Zeolites

• Zeolites are flushed with sodium ions

• When hard water is flushed through then the sodium trades places with unwanted ions.

http://www.zeobrite.com/consumer.asp

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Limestone• Limestone is ______• Common stone found in ____

– ____ in the atmosphere causes rain to be slightly ______

– Slight ______of rain dissolves ______

– In caverns, the solution drips and eventually the water evaporates

– Leaving behind __________ and ___________

http://dnr.state.il.us/lands/landmgt/PARKS/R4/caverns/Cave.htm