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 SiO 4 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 Gemstones courtesy of Dr. Wacholtz

Tourmalines (Na,Ca)(Mg, Fe, Al, Mn, Li) 3 Al 6 (BO 3 ) 3 (Si 6 O 18 )(OH,F) 4

Beryls Be 3 Al 2-x (Cr, Fe) x Si 6 O 18

Absorbance of Emeralds (fig 10.25)

Zn 2+ tetrahedral complexes Courtesy of Dr. Wacholtz Wavelength Transmitted/ reflected ~580 nm~605 nm ~565 nm Wavelength Absorbed (d-d) transition ~600~610 ~640 (note the ligands absorb in the UV to blue range nm

Review-Chapter 9 attractive interactions among molecules: –ion-ion (lattice energy: U=k(Q 1 Q 2 /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 2 O, 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: P vap = X solv P˚ solv Note: X solv =n solv /(n solv + in solute ) 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: ● V cubic = 8r 3, – 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 SiO 4 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, octahedral tetrahedral –High spin versus low spin states.