Solutions/Answers to Exercises

Exercise 1. Draw an orbital box diagram for the electrons in a neutral Br atom. Assign quantum numbers to the electrons in the valence shell.

Quantum numbers for the valence shell electrons;

n = 4, l = 0, m_l = 0, m_s = +1/2
n = 4, l = 0, m_l = 0, m_s = -1/2
n = 4, l = 1, m_l = -1, m_s = +1/2
n = 4, l = 1, m_l = -1, m_s = -1/2
n = 4, l = 1, m_l = 0, m_s = +1/2
n = 4, l = 1, m_l = 0, m_s = -1/2
n = 4, l = 1, m_l = +1, m_s = +1/2

Exercise 2. Write the full electron configuration for Pd. Write the shorthand notation for Pd.

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d⁸

[Kr]5s²4d⁸

Exercise 3. Write an electron configuration for Cd.

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰
[Kr]5s²4d¹⁰

Exercise 4. Write both a full and shorthand electron configuration for Hg.

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰6s²4f¹⁴5d¹⁰
[Xe]6s²4f¹⁴5d¹⁰

Exercise 5. Assign quantum numbers to the valence shell electrons in Cr.

Chromium has an anomalous electron configuration of [Ar]4s¹3d⁵

n = 4, l = 0, m_l = 0, m_s = +1/2
n = 3, l = 2, m_l = -2, m_s = +1/2
n = 3, l = 2, m_l = -1, m_s = +1/2
n = 3, l = 2, m_l = 0, m_s = +1/2
n = 3, l = 2, m_l = +1, m_s = +1/2
n = 3, l = 2, m_l = +2, m_s = +1/2

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