Date post: | 02-Jan-2016 |
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Announcements
● Exam Friday.
● Review Materials Posted.
● Graded quizzes available outside Dr. Gutow's office.
● If you instructor has not previously arranged to return your lab notebooks they are outside Dr. Gutow's office.
To join clicker to class today:
– Turn on the Clicker (the red LED comes on).
– Push “Join” button followed by “20” followed by the “Send” button (switches to flashing green LED if successful).
Review• Molecular solids=Isolated molecules held together
by intermolecular forces.• Network solids
– diamond = continuous network of covalent bonds.– Silicates = networks of SiO4 tetrahedra held together
by ionic interactions (ex. minerals and clays).• band structure of solids
– Conductors, semiconductors and non-conductors.– Shift in band gap caused by small amounts of
impurities (ex. yellow diamond). • Intro to crystal field splitting in discussion.
Zn2+ tetrahedral complexesCourtesy of Dr. Wacholtz
WavelengthTransmitted/reflected
~580 nm ~605 nm~565 nmWavelengthAbsorbed(d-d) transition
~600 ~610 ~640
(note the ligands absorb in the UV to blue range 350-400 nm
Review-Chapter 9• attractive interactions among molecules:
– ion-ion (lattice energy: U=k(Q1Q2/d), calculation of U from a cycle of reactions)
– ion-dipole
– dipole-dipole
– dipole - induced dipole– Dispersion
Review-Chapter 9• H-bonding
– Generally weaker than ion-ion interactions– Stronger than other intermolecular interactions.– Only seen for hydrogens bonded to N, O or F.– Bond to lone pair on another molecule (usually on N,
O or F).– Explain very high boiling points for H
2O, NH
3 and HF
• Solubility– “like dissolves like” (polar in polar, nonpolar in
nonpolar)– Only soluble if dissolved particles lower energy than
undissolved solid.
Review-Chapter 9• Raoult’s law: Pvap = XsolvP˚solv
• Note: Xsolv=nsolv
/(nsolv
+ insolute
)
• Reading phase diagrams
• Water’s unusual properties explained primarily by strong directional hydrogen bonding. – expansion on freezing – formation of a meniscus– surface tension – capillary action
Review-Chapter 10• Crystalline solids
– cubic, bcc and fcc lattices
– Volumes of different lattices in terms of radius of atoms:
● Vcubic
= 8r3,
– In ionic lattices smaller ion usually fits into octahedral or tetrahedral holes
• small (+) ion < 44% radius of big ion into tetrahedral holes
• if (+) ion about same size as (-) ion get simple cubic, like CsCl.
Review – Chapter 10• Molecular solids=Isolated molecules held together
by intermolecular forces.• Network solids
– diamond = continuous network of covalent bonds.– Silicates = networks of SiO4 tetrahedra held together
by ionic interactions (ex. minerals and clays).• band structure of solids
– Conductors, semiconductors and non-conductors.– Shift in band gap caused by small amounts of
impurities (ex. yellow diamond).