Transcript Ch 23: metals

CH 23: METALS
Chapter 23
METALS
General Properties and Structure of Metals
•
•
•
•
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.
© 2014 Pearson Education, Inc.
General Properties and Structure of Metals
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.
Energy
Conduction Band
Valence Band
Large band gap
Small band gap
Conductor
© 2014 Pearson Education, Inc.
Semi-conductor
Insulator
General Properties and Structure of Metals
• 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)
© 2014 Pearson Education, Inc.
Distribution of Metals in Earth
•
•
•
•
•
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.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
Mineral Sources of Common Metals
• NaCl = halite; KCl = sylvite
 Both recovered from evaporated sea water
• Fe2O3 = hematite; TiO2 = rutile; SnO2 = cassiterite
• PbS = galena; HgS = cinnabar; ZnS = sphalerite;
MoS = molybdenite; VS4 = patronite
• [Pb5(VO4)3Cl] = vanadinite
 Found mainly at upper levels of galena mines
• [K2(UO2)2(VO4)2 ∙ 3 H2O] = carnotite
 Found as crusts or flakes with sandstone
 Source of V, U, and Ra (because Ra is found with U)
• [Fe(NbO3)2] = columbite; [Fe(TaO3)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
• 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.
© 2014 Pearson Education, Inc.
Alloy Composition
• 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
© 2014 Pearson Education, Inc.
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 ___________________
© 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
© 2014 Pearson Education, Inc.
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
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
___________
© 2014 Pearson Education, Inc.
http://dnr.state.il.us/lands/landmgt/PARKS/R4/caverns/Cave.htm