Home exercises

Chapter 1

1. The wavelength of the green light from a traffic signal is centered at 522 nm. What is the frequency of this radiation ?

2. Calculate the energy (in joules) of a) a photon with a wavelength of 5.00x104 nm (Infrared region)b) a photon with a wavelength of 5.00x10-2 nm

3. The energy of a photon is 5.87x10-20 J. What is the wavelength (in nanometers)

4. What is the wavelength of a photon emitted during a transition from the n i=5 state to the nf = 2 in the hydrogen atom ?

5. Calculate the wavelength in the following two cases:* The wavelength of an electron traveling at 1.24x107 m/s. me = 9.1x10-31 kg * The wavelength of a baseball of mass 149g traveling at 41.3m/s

6. Calculate the wavelength of the “particle” in the following two cases:a) The fastest serve in tennis is about 62 m/s. Calculate the wavelength associated with a

6.0x10-2 kg tennis ball traveling at this velocityb) Calculate the wavelength associated with an electron moving at 62 m/s

7. How many individual orbitals are there in the third shell ? Write out n, l, m l

quantum numbers for each one and label each set by the s, p, d, f designations8. An electron in a certain atom is in the n=2 quantum level. List the possible values of l

and ml that it can have.9. List all the possible subshells and orbitals associated with the principle quantum

number n, if n=510. Indicate which of the following sets of quantum numbers in an atom are unacceptable

and explain why: (a) (1,0,1/2,1/2) (b) (3,0,0,+1/2) (c) (2,2,1,+1/2) (d) (4,3,-2,+1/2) (e) (3,2,1,1,)

11. Indicate the number of unpaired electrons present in each of the following atoms: B, Ne, P, Sc, Mn, Se, Kr, Fe, I, Pb, Cd.

12. Draw the shapes (boundary surfaces) of the following orbitals: a) 2py, b) 3

c) 3d13. Draw orbital diagrams for atoms with the following configuration:

a) 1s22s22p5 b) 1s22s22p63s23p3 c) 1s22s22p63s23p64s23d7

14. The ground- state electron configurations listed here are incorrect. Explain what mistakes have been made in each and write the correct electron configurations

Al: 1s22s22p43s23p3

B: 1s22s22p5

F: 1s22s22p6

15. Without referring to a periodic table, write the electron configuration of the elements with the following atomic numbers: a) 9; b) 20; c) 26; d) 33. Classify the elements.

16. Specify the group of the periodic table in which each of the following elements is found: a) [Ne] 3s1, b) [Ne]3s23p3, c) [Ne]3s23p6, d) [Ar]4s23d8

17. A M2+ ion derived from a metal in the 1st transition metal series has four electrons in the 3d subshell. What element might M be?

18. In general, ionization energy increases from left to right across a given period. Aluminum, however, has a lower ionization energy than magnesium. Explain.

19. Two atoms has the electron configurations 1s22s22p6 and 1s22s22p63s1. The first ionization energy of one is 2080 KJ/mol, and that of the other is 496 KJ/mol. Match each ionization energy with one of the given electron configurations. Justify your choice ?

20. A hydrogenlike ion is an ion containing only one electron. The energies of the electron in a hydrogenlike ion are given by

Where n is the principle quantum number and Z is the atomic number of the element. Calculate the ionization energy of the He+ ion

21. From the following data, calculate the average bond energy for the N-H bond:NH3(g) NH2(g) + H(g) Ho = 435KJNH2(g) NH(g) + H(g) Ho = 381 KJNH(g) N(g) + H(g) Ho = 360 KJ

22. The energy needed for the following process is 1.96x104KJ.mol-1:Li(g) Li3+ (g) + 3e-

If the first ionization energy for lithium is 520 kJ/mol-1, calculate the second ionization energy of lithium, that is, the energy required for the processLi+(g) Li2+(g) + e-

(Use the equation: )

Plan:Li(g) - 1e Li+(g) IE1 = 520 KJ.mol-1

Li+(g) - 1e Li2+(g) IE2 = ?Li2+(g) - 1e Li3+(g) IE3

= -------------------------------Li(g) Li3+(g) +3e IE1+IE2+IE3 = 1.96x104KJ.mol-1 or 520 +IE2+IE3 = 1.96x104

Calculate IE3 = with Z=3 and n=1

IE2= 1.96x104-520-

23. According to VB theory, explain, why the nitrogen atom cannot have pentavalence,

while the phosphorus has ?

24. Determine and explain all possible valences of the following atoms: S, Cl, C

25. Draw a Lewis formula for the following species: H2O, H3O+, NF3, OF2, BF3, [BF4]-,

SF4, SF6

26. What is the hybridization of the central atom in each of the following: NCl3, CF4, SF6,

NH3, NH4+,

27. What hybridizations are predicted for the central atoms in the following molecules:

H2O H2S H2Se H2Te

104.5o 92.2o 91o 89.5o

Why the bond angles decrease by the above order ?

28. Predict geometry of the following molecules: H2O, H3O+, CH4, CO2, SO2, BF3.

29. Describe the hybridization of N in each of these species:

i) NH3; ii) NH4+; iii) ; iv) ; v)

30. What change in hybridization occurs in the following reaction?

NH3 + BF3 →H3N: BF3

31. Briefly discuss the bond angles in the hydroxylamine molecule in terms of the ideal

geometry and the small changes caused by electron-pair repulsions

32. Predict geometry of the following molecules: H2O, H3O+, CH4, CO2, SO2, BF3.

33. Describe the hybridization of N in each of these species:

ii) NH3; ii) NH4+; iii) ; iv) ; v)

34. What change in hybridization occurs in the following reaction?

NH3 + BF3 →H3N: BF3

35. Briefly discuss the bond angles in the hydroxylamine molecule in terms of the ideal

geometry and the small changes caused by electron-pair repulsions

31.