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.

Some Silicate Gemstonescourtesy of Dr. Wacholtz

Tourmalines(Na,Ca)(Mg, Fe, Al, Mn, Li)3Al6(BO3)3(Si6O18)(OH,F)4

BerylsBe3Al2-x(Cr, Fe)xSi6O18

Absorbance of Emeralds(fig 10.25)

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).

Review – Chapter 10• Crystal field theory

– Ligands around a transition metal ion cause the d-orbitals to lose their degeneracy.

– You are responsible for two ligand arrangements, octahedraltetrahedral

– High spin versus low spin states.