Chemistry Problem Set: Ionization Energies and Electron Configurations - Prof. R. Berger, Assignments of Inorganic Chemistry

Problem set questions from a university-level chemistry course. The questions cover topics such as ionization energies, electron configurations, and the periodic table. Students are required to answer directly on the sheet and provide explanations for some questions. The first question asks about the group of an element based on its ionization energies, the second question deduces the electron configuration of an element yet to be discovered, and the third question calculates the fourth ionization energy and wavelength of a photon using bohr's model.

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Pre 2010

Uploaded on 08/19/2009

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8s 8p 8d 8f 8g . . . . . .
7s 7p 7d 7f 7g . . . .
6s 6p 6d 6f 6g . .
5s 5p 5d 5f 5g
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
Chemistry 218
Name___Crib__________________________ Problem Set #1
This problem set is due by the end of class on Friday, January 21st. Please begin answering the questions
directly on this sheet and add as many additional sheets as necessary. Where an explanation is
requested, the majority of the points depend on the explanation. For quantitative problems, all
work must be shown.
1. Consider the real element with the following successive ionization energies:
Ionization Energies (MJ @ mol!1)
I II III IV VVI VII VIII IX X
0.7865 1.5771 3.2316 4.3555 16.091 19.785 23.786 29.252 33.877 38.733
To what group does this element belong? Briefly explain your reasoning.
On the basis of the relatively large increase between IE4 and IE5, it is most
likely that the fifth ionization involves a core electron rather than a valence
electron. As a result, there are four valence electrons. The group in the periodic
table whose atoms have only one valence electron is group IV (14). Therefore the
element is a member of group 14. (The ionization energies belong to silicon).
2. Element 117, which has yet to be discovered, will be a member of the halogen family. What will be
the atomic number of the halogen immediately below element 117? Explain. Deduce the full (i.e., no
shorthand notation) ground state electron configuration of the element immediately below element 117.
We can expand the normal diagonal filling order as
shown to the right. Beginning in the n = 5 shell, g
orbitals can be populated. This means that the filling
order will be
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s
5f 6d 7p 8s 5g 6f 7d 8p
The halogens all have an ns2 np5 valence shell
configuration, so the electron configuration of the
halogen below element 117 would be:
pf3

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8s 8p 8d 8f 8g...... 7s 7p 7d 7f 7g.... 6s 6p 6d 6f 6g.. 5s 5p 5d 5f 5g 4s 4p 4d 4f 3s 3p 3d 2s 2p 1s

Chemistry 218

Name___Crib__________________________ Problem Set #

This problem set is due by the end of class on Friday, January 21 st. Please begin answering the questions directly on this sheet and add as many additional sheets as necessary. Where an explanation is requested, the majority of the points depend on the explanation. For quantitative problems, all work must be shown.

  1. Consider the real element with the following successive ionization energies:

Ionization Energies (MJ @ mol!^1 ) I II III IV V VI VII VIII IX X 0.7865 1.5771 3.2316 4.3555 16.091 19.785 23.786 29.252 33.877 38.

To what group does this element belong? Briefly explain your reasoning.

On the basis of the relatively large increase between IE 4 and IE 5 , it is most likely that the fifth ionization involves a core electron rather than a valence electron. As a result, there are four valence electrons. The group in the periodic table whose atoms have only one valence electron is group IV (14). Therefore the element is a member of group 14. (The ionization energies belong to silicon).

  1. Element 117, which has yet to be discovered, will be a member of the halogen family. What will be the atomic number of the halogen immediately below element 117? Explain. Deduce the full (i.e., no shorthand notation) ground state electron configuration of the element immediately below element 117.

We can expand the normal diagonal filling order as shown to the right. Beginning in the n = 5 shell, g orbitals can be populated. This means that the filling order will be

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s 5g 6f 7d 8p

The halogens all have an ns^2 np^5 valence shell configuration, so the electron configuration of the halogen below element 117 would be:

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2 4f^14 5d^10 6p^6 7s^2 5f^14 6d^10 7p^6 8s^2 5g^18 6f^14 7d^10 8p^5.

Its atomic number is 167.

  1. Be3+^ is a hydrogen-like species. Use Bohr’s model of the atom to calculate the fourth ionization energy, IE 4 , for a Be atom. Compare this value to the tabulated value of the fourth ionization energy of Be, IE 4 = 21.0065 MJ @ mol!^1. Use the value that you calculated above to calculate the wavelength of the photon that must be absorbed to remove the electron from a Be3+^ ion. Hint: You may want to consult your general chemistry text.

Note: The fourth ionization energy of Be should have been given in MJ @ mol!^1.

The fourth ionization process for Be corresponds to the removal of the single

remaining electron from the n = 1 level to n = 4. The energy of an electron in

any energy level of a hydrogen-like atom is given by the Rydberg relation:

where Z is the atomic number, RH is the rydberg constant, 2.179 x 10!^18 J, and

n is a positive integer. The energies of the electron in the n = 1 and n = 4 levels

of Be3+^ are therefore:

The 4th^ ionization energy of Be is therefore:

0! (!3.486 x 10!^17 J) = 3.486 x 10!^17 J

The wavelength of this photon is given by: