CH 23: METALS

METALS Chapter 23

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. General Properties and Structure of Metals Conduction Band Valence Band Energy ConductorSemi-conductorInsulator 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.

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. 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 = sylvite Both recovered from evaporated sea water Fe 2 O 3 = hematite; TiO 2 = rutile; SnO 2 = cassiterite PbS = galena; HgS = cinnabar; ZnS = sphalerite; MoS = molybdenite; VS 4 = patronite [Pb 5 (VO 4 ) 3 Cl] = vanadinite Found mainly at upper levels of galena mines [K 2 (UO 2 ) 2 (VO 4 ) 2 ∙ 3 H 2 O] = carnotite Found as crusts or flakes with sandstone Source of V, U, and Ra (because Ra is found with U) [Fe(NbO 3 ) 2 ] = columbite; [Fe(TaO 3 ) 2 ] = tantalite Found in mixed deposits

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. S-Block Elements Properties: – _____________ – _________________ – Alkali metals react violently with ________ – React with _______________ Trends – _________ atoms on Periodic Table – Least ______________ and ___________________

© 2014 Pearson Education, Inc. S-block Elements—Flame Tests Petrucci, et al. General Chemistry.

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. Hard Water Caused by _______________________ – _______________________ – ______________ hardness: ______ is present – ______________ hardness: any other ions present Water softening – Replaces ___________ with other ions – Uses _____________________

© 2014 Pearson Education, Inc. 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.

© 2014 Pearson Education, Inc. 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 ___________