The University of the West Indies (Mona)
Department of Chemistry
Preliminary Chemistry A (Chem 0901)
Atomic Structure: Tutorial 2
For discussion in the week beginning September 24, 2012.
Answers should be submitted by 9:00 am on Monday September 24, 2012 in the box provided. Please write your ID number and Laboratory day clearly on your script. 1. Give an expression for the Balmer-Rydberg equation in terms of wavelength λ, the Rydberg constant R, and the integers m and n where m < n.
 a. Using the equation calculate the wavelength (in nanometers) of the first line of the Lyman series (m = 1).
 b. To which region of the electromagnetic spectrum does this wavelength correspond ?
 c. Using the Balmer-Rydberg equation, at what value of n does the red line (wavelength = 656.3 nm) in the Balmer series of the hydrogen emission spectrum occur.
 2. Calculate the wavelength of the following:
a. A photon of energy 2.89 x 10-19 J
b. An electron travelling at 1/5 of the speed of light
 c. A 70 kg man running a 100 m sprint in 9.84 s.
 i. In parts b. and c., how does the wavelength compare to the region in which the “particle” is confined?
 ii. Based on your answer in part c, how significant is the man’s wave-like properties? Briefly explain.
 3. Write the expression for the Heisenberg Uncertainty Principle (HUP).
 a. Determine the uncertainty in the path of flight of an 8.040 g bullet if its velocity is 360 ± 1 ms-1. (Hint: the mass is known with high precision therefore Δmv = mΔv)
 b. Determine the uncertainty in the position of an electron if the velocity is 5.80 ± 0.02 × 106 ms-1.
(Use the hint given above)
 i. How does the error in the position of the “particles” in a. and b. compare to the space they occupy?
For an electron of principal quantum number n...
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