1. The blue color of the sky results from the scattering of sunlight by air molecules. The blue light has a frequency of about 7.5 × 1014 Hz. (a) Calculate the wavelength, in nm, associated with this radiation, and (b) calculate the energy, in joules, of a single photon associated with this frequency. (8 points)

2. (a) What is an energy level? Explain the difference between ground state and excited state. (b) What are emission spectra: How do line spectra differ from continuous spectra?   (6 points)

3. Explain the statement, Matter and radiation have “dual nature.” (3 points)

4.  Which of the four quantum numbers (n, ℓ, mℓ, ms) determine (a) the energy of an electron in a hydrogen atom and in a many-electron atom, (b) the size of an orbital, (c) the shape of an orbital, (d) the orientation of an orbital in space. (4 points) 

5. Determine the maximum number of electrons that can be found in each of the following subshells: 3s, 3d, 4p, 4f. (2 points) 

6. How many electrons would fill the third energy level (n = 3)? (2 points) 

7. Explain the meaning of the symbol 4d6. (2 points) 

8. For each of the following pairs of subshells, indicate which is higher in energy: (a) 2s or 2p, (b) 3d or 4p, (c) 4s or 4p, (d) 3d or 4s. (4 points) 

9. Explain the meaning of diamagnetic and paramagnetic. Give an example of an element that is diamagnetic and one that is paramagnetic. What does it mean when we say that electrons are paired? (3 points) 

10. Write the ground-state electron configurations for the following elements: (12 points) 

11. The electron configuration of a neutral atom is 1s22s22p63s2. Name the element. (2 points) 

12. A 368 g sample of water absorbs infrared radiation at 1.06 × 104 nm from a carbon dioxide laser. Suppose all the absorbed radiation is converted to heat. Calculate the number of photons at this wavelength required to raise the temperature of the water by 5.00ºC.  (4 points) 

13. Draw orbital diagrams for atoms with the following electron configurations: (9 points) 

a. 1s22s22p5 

b. 1s22s22p63s23p3 

c.   1s22s22p63s23p64s23d7  14. Define the following terms and principles: (8 points) 

a. Heisenberg uncertainty principle 

b.  Aufbau principle 

c. Pauli exclusion principle

d.   Hund’s rule 

15. What are valence electrons? How many valence electrons do each of the following elements have: (a) H, (b) Ca, (c) Al, (d) N, (e) O, (f) Cl, (g) He, and (h) Ne? (4 points) 

16. In the periodic table, the element hydrogen is sometimes grouped with the alkali metals and sometimes with the halogens. Explain why hydrogen can resemble the Group 1A and the Group 7A elements. (2 points) 

17. Group the following electron configurations in pairs that would represent similar chemical properties of their atoms: (3 points) 

18. Write the ground-state electron configurations of the following ions: (12 points) 

19. Which of the following species are isoelectric with each other? C, Cl–, Mn+2, B–, Ar, Zn, Fe+3, Ge+2. (4 points) 

20. On the basis of their positions in the periodic table, select the atom with the larger atomic radius in each of the following pairs: (4 points)

21. Why do elements that have high ionization energies also have more positive electron affinities? Generally, which elements have the highest ionization energies? Which elements would have the lowest? (2 points)