## Atom and Atomic Spectra

1. Excited sodium atoms may emit radiation having a wavelength of 589 nm.

2. a) What is the wavelength in meters?   b) What is the frequency of this light?
c) What region of the spectrum is this in?   d) What is the energy of this light?
3. How does quantum theory explain the fact that excited potassium atoms emit light at only a relatively few wavelengths?
4. Draw the orbital diagrams for O and Si. How many unpaired electrons are in each of these?
5. Of the following electron configurations, state whether each represents an atom in the ground state, a possible excited state, or is incorrect.

6. a) 1s22s22p1   b) 1s22s13s1   c) 1s22s22p63s22d2   d) 1s22s42p2   e) 1s12s1
7. A radio station has a frequency of 96.5 MHz. Find the wavelength and E.
8. Microwaves have a frequency of around 2.5 GHz. What is the wavelength? (1 GHz = 109 Hz)
9. What is the energy associated with 688 nm light? What color light is this?
10. A certain photon of radiation has energy of 4.65 x 10-15 J. What is the wavelength of this light, in nm?
11. A certain light has an energy of 4.56 x 10-19 J. What color is this light? (Hint: find wavelength in nm.)

Answers to select problems: 1a) 5.89 x 10-7b) 5.09 x 1014 Hz   d) 3.37 x 10-19 J   5) wavelength = 3.11 m E=6.39 x 10-26 J

6) 0.12 m   7) 2.89 x 10-19 J, red   8) .0427 nm   9) violet (436 nm)

## The Atom and Atomic Spectra Review Questions

1. An unknown substance has a mass of 3.44 grams and a volume of 2.77 mL. What is its density?
2. The density of dry air at 25 °C is 1.19 x 10-3 g/cm3. What is the volume of 50.0 grams of air?
3. List the four main ideas of Dalton's atomic theory.
4. How were electrons discovered and by whom?
5. Describe Rutherford's gold foil experiment.
6. For the following elements, give the number of protons, electrons, and neutrons.

7. a) Ba   b) Cu   c) F
8. What is an isotope?
9. The four main isotopes of chromium have the following abundances: 50Cr = 4.35% ,52Cr = 83.79%, 53Cr = 9.50%, 54Cr =2.36%. What is the average atomic mass?
10. Chlorine has two main isotopes,35Cl and 37Cl. If the average atomic mass is 35.453, find the abundances of each isotope.
11. State the differences between the following atomic models: J.J. Thomson's, Rutherford's, Bohr's, Quantum mechanical model.
12. What is an atomic orbital?
13. What is the shape of an s orbital? a p orbital? How many electrons do each of these hold?
14. Define the Aufbau principle, Pauli exclusion principle, and Hund's rule.
15. Give the electron configuration for each of the following elements, both longhand and shorthand:

16. a) S   b) Rb   c) Au
17. Draw the electron configurations for: a) S   b) Na   c) B
18. List the colors in the visible spectrum from lowest wavelength to highest wavelength.
19. Explain where the different emission lines in the hydrogen spectrum come from.
20. What is the frequency of light whose wavelength is 5.66 x 10-7 m?
21. What is the energy of light with a frequency of 7.22 x 1015Hz?
22. What is the energy of light with a wavelength of 4.22 x 10-6 m?
23. Define ground state and excited state.
24. What is Heisenberg's uncertainty principle?
25. What was the main idea behind de Broglie's work?
26. What is the photoelectric effect? Give an example.