Ionic and covalent Bonding and Properties of Solids. Chemical Bonding sites. The Orbitron: a gallery of atomic orbitals and molecular orbitals on the WWW http://www.shef.ac.uk/chemistry/orbitron/ Excellent sites for shapes of molecules: http://www.chemmybear.com/shapes.html.
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The Orbitron:a gallery of atomic orbitals and molecular orbitals on the WWWhttp://www.shef.ac.uk/chemistry/orbitron/Excellent sites for shapes of molecules:http://www.chemmybear.com/shapes.html
Electron pairs repeland molecules adjust their shapes so that
their valence shell electrons are as far apart as possible
Each “-” between atoms represents a shared pair of electrons
Bond type determined by difference in electronegativity and molecular shape
Polarizability α = 1.48 x 10-24 cm3
Unit cell: the smallest representation of a crystal that
reproduces the whole crystal.
(do not memorize this table!)
(A and B are same type of atom)
Coordination number is 12
(number of nearest neighbors
for each atom; 6 in same plane
and 3 above and 3 below)
(the other major structure
is cubic close-packed;
Al, Cu, Ag, Au)
* don’t memorize these! No way!
NaCl unit cell (coordination # 6)
Note: anions and cations are different sizes!
Graphite: hexagonal rings of sp2 hybridized carbons
Others: Diamond, ceramics
Harder and stronger, but less conductive
2 NO N2 + O2
2 CO + O2 2 CO2
hydrocarbons + O2
CO2 + H2O
honeycomb ceramic coated with Pt, Pd, Rh
No current across
junction with this set-up