11. The work function (see Problem 10) for lithium metal is 55.7 kcal . How does this compare with the first ionization energy of gaseous Li atoms? What is the longest-wavelength light that could be used in a lithium photocell?

12. Copper has a work function of 92.3 kcal . Can electrons be ejected from copper by visible light? If not, what types of radiation could?

13. The maximum wavelength for emission from a cesium photocell is 6200 . What is the work function for cesium metal?

14. In the Bohr model of the hydrogen atom, what is the radius of the electron orbit for quantum number n=2? What is the energy of this quantum state? What is the energy of state n=3?

15. What is the energy difference between states n=2 and n=3 of the hydrogen atom? What is the wavelength of radiation absorbed when the hydrogen atom jumps from n=2 to n=3? In what part of the electromagnetic spectrum does this occur?

16. Calculate the wavelengths of the hydrogen atom transitions from =2 to
n=3, 4, 5, 6, 7, and (infinity). Plot these along a wavelength scale. Notice how the lines become closer and closer together as the upper quantum number n increases.