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Unformatted text preview: fewer than 8 electrons, but all the terminal atoms are sa?sﬁed, add e‐ pairs to central atom. If a central atom has fewer than 8 electrons (and it is not an excep?on to the octect rule) a mul?ple bond is likely. Move electrons from outer atoms to form mul?ple bonds. (double is 2 shared pairs, triple is 3 shared pairs) Check that your structure is the best possible arrangement of atoms using the formal charge check. FC= V – (L + ½ S) or FC = group number – (# unpaired e‐ + # of bonds). FC should be nearest 0 for all atoms, total FC is 0 for neutral compounds, should = charge on polyatomic ion. More than one “iden?cal structure” may have resonance. Some excep?ons include expanded valence, radicals and incomplete octet. Examples • O2 • NH3 Examples • COCl2 • AsH3 Electromagne?c Radia?on and MaRer Dobson Units – Amount of UV radia?on reaching a detector at ground level is correlated to the amount of ozone in the column Fundamental Proper?es of Light Electromagne?c Spectrum Electromagne?c Spectrum Longer wavelength = lower
Shorter wavelength = higher
frequency/energy ROY G BIV Majority of radiation is infrared red Radia?on in Terms of Energy • Photons – bundles of energy E = hc λ Interac?on of Radia?on with MaRer • IR • Vis • UV UV radia?on can break some chemical bonds What’s so special about ozone? • Why doesn’t UV break all bonds? • Is all UV the same? Think about visible light… is all visible light the same? Is all UV radia?on the same? There is a spectrum of UV radia?on just like there is a...
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