3313Q1Sp02 - .. What does this reveal about its properties?...

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ENSC 3313, Spring 2002 Quizl Answer any 4 Questions only, 1 point each Ql. Studies indicate that the intensity of green light decays exponentially as it passes through sea water. The intensityat 1.0 meter below the surface is one quarter of the surface intensity. At what depth has the intensity decreased to one tenth compared to the surface intensity? I = Ioe- JL x I At x = 1.0 m, -= 0.25 I o 1n(0.25) = -Ji. (1.0 m) =:> Ji.= 1.386 m-l Decreased to 1/10 I I = 0.1 = e-1.386x o x = 1.66 m Wavelengths shorter than 225 nanometers are strongly absorbed by the valence electrons of diamond's carbon atoms, which then move to the conduction band and can produce a "response" signal. What band gap, E, ( energy change ~E) does this correspond to? Answer in electron volts please. Know that Planck's constant, h = 0.662 x 10-33 J.s, and leV = 0.160 x 10-18 J. The velocity of light = 0.299 x 109 mls. 2. Substituting AB = = 5.5 eV Write down the likelyelectron shell structure of promethium, of atomic number 61. Begin ls22s22p6.
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Unformatted text preview: .. What does this reveal about its properties? 3 The superscripts sum to 61 We have a partly filled f shell, hence a rare earth metal. It is likely to have a variable valency and be reactive. . 4. d '-To illustrate what ~ did I show this diagram on the overhead projector at this time? What is the contrast with? * Directional bonding leads to directional properties. * The properties of graphite in the basal plane are very .different to the properties in the direction perpendicular to that plane, for example, stiffness, electrical and theffi1al conductivity. * The contrast is with cubic diamond. 5. A polyethylene molecule can be represented as -[-CH2CH2-]-no What degree of polymerization would be required to give a molecule of molecular weight 50,008 amu? MW = nxmass/mer mass/mer 6. What is the purpose of the two Callister text diagrams? He is contrasting covalent and metallic bonding....
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3313Q1Sp02 - .. What does this reveal about its properties?...

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