practice-midterm-ii-key

practice-midterm-ii-key - Problem 1 (40 points) [One...

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Problem 1 (40 points) [One sentence questions] Helium (He) and argon (Ar) are stored in a container. What is the ratio of the speed of He to Ar? (6 points) √( U rms He / U rms Ar )= √[( 39.948g/mol)/(4.0026g/mol)] = 3.16 Following the question above, if these two gases are allowed to effuse into a vacuum chamber next to the container, which gas completes the effusion first? (4 points) The one with the smaller mass. Helium. How does an electromagnetic wave make electrons “jump” between energy levels (orbitals) of an atom? (6 points) Because the oscillating electric field of the waves can move electrons, which are very light and can follow the electric field because they are charged. -ting Electrons are very light and its charge allows it to jump between energy levels of the oscillation electric field. -baby After solving the Schrodinger equation for hydrogen atoms, you will get the energies and wavefunctions. Give the energy of the most stable orbital and draw the shape of it. (8 points) 1s Draw a 3 p orbital, and indicate the nodes (or nodal planes). Mark the location of the nucleus. (8 points) Two nodes: one nodal plane through the nucleus and dividing the two lobes, and another nodal sphere cutting through the middle of two lobes. If the effective nuclear charge for the electrons in 2 p orbitals is smaller than that in a 2 s orbital, which orbital is more stable? Write down the equation you use in your reasoning.
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This note was uploaded on 04/29/2008 for the course CHE 2a taught by Professor Tingguo during the Winter '08 term at UC Davis.

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practice-midterm-ii-key - Problem 1 (40 points) [One...

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