Chapter 9

The highest first ionization energy of the following is that of (a) \(\mathrm{Cs}_{i}\) (b) \(\mathrm{Cl}_{i}\) (c) I; (d) Li.

The most negative electron affinity of the following elements is that of (a) \(\mathrm{Br} ;\) (b) \(\mathrm{Sn} ;\) (c) \(\mathrm{Ba} ;\) (d) Li.

An ion that is isoelectronic with \(\mathrm{Se}^{2-}\) is (a) \(\mathrm{S}^{2-} ;\) (b) I \(^{-}\) (c) \(\mathrm{Xe} ;\) (d) \(\mathrm{Sr}^{2+}.\)

Write electron configurations to show the first two ionizations for Cs. Explain why the second ionization energy is much greater than the first.

Explain why the first ionization energy of \(\mathrm{Mg}\) is greater that of \(\mathrm{Na},\) whereas the second ionization of Na is greater than that of Mg.

Answer each of the following questions: (a) Which of the elements \(P, A s,\) and \(S\) has the largest atomic radius? (b) Which of the following has the smallest radius: \(\mathrm{Xe}, \mathrm{O}^{2-}, \mathrm{N}^{3-},\) or \(\mathrm{F}^{-} ?\) (c) Which should have the largest difference between the first and second ionization energy: \(\mathrm{Al}, \mathrm{Si}, \mathrm{P},\) or \(\mathrm{Cl} ?\) (d) Which has the largest ionization energy: \(\mathrm{C}, \mathrm{Si}\), or \(\mathrm{Sn}\) ? (e) Which has the largest electron affinity: \(\mathrm{Na}, \mathrm{B}\) \(\mathrm{Al},\) or \(\mathrm{C} ?\)

For the atom \(^{119} \mathrm{Sn}\), indicate the number of (a) protons in the nucleus; (b) neutrons in the nucleus; (c) \(4 d\) electrons; (d) 3s electrons; (e) 5 \(p\) electrons; (f) electrons in the valence shell.

Give the symbol of the element (a) in group 14 that has the smallest atoms; (b) in period 5 that has the largest atoms; (c) in group 17 that has the lowest first ionization energy.

Refer only to the periodic table on the inside front cover and indicate which of the atoms, \(\mathrm{Bi}, \mathrm{S}, \mathrm{Ba}, \mathrm{As}\) and \(\mathrm{Ca},\) (a) is most metallic; (b) is most nonmetallic; (c) has the intermediate value when the five are arranged in order of increasing first ionization energy.

Arrange the following elements in order of decreasing metallic character: \(\mathrm{Sc}, \mathrm{Fe}, \mathrm{Rb}, \mathrm{Br}, \mathrm{O}, \mathrm{Ca}, \mathrm{F}, \mathrm{Te}.\)

In multielectron atoms many of the periodic trends can be explained in terms of \(Z_{\text {eff }}\) Consider the following statements and discuss whether or not the statement is true or false. (a) Electrons in a \(p\) orbital are more effective than electrons in the \(s\) orbitals in shielding other electrons from the nuclear charge. (b) \(\mathrm{Z}_{\text {eff }}\) for an electron in an \(s\) orbital is lower than that for an electron in a \(p\) orbital in the same shell. (c) \(Z_{\text {eff }}\) is usually less than \(Z.\) (d) Electrons in orbitals having \(\ell=1\) penetrate better than those with \(\ell=2.\) (e) \(\mathrm{Z}_{\text {eff }}\) for the orbitals of the elements \(\mathrm{Na}(3 s)\) \(\mathrm{Mg}(3 s), \mathrm{Al}(3 p), \mathrm{P}(3 p),\) and \(\mathrm{S}(3 p)\) are in the order \(Z_{\text {eff }}(\mathrm{Na})<\mathrm{Z}_{\text {eff }}(\mathrm{Mg})>\mathrm{Z}_{\text {eff }}(\mathrm{Al})<\mathrm{Z}_{\text {eff }}(\mathrm{P})>\mathrm{Z}_{\text {eff }}(\mathrm{S}).\)

Consider a nitrogen atom in the ground state and comment on whether the following statements are true or false. (a) \(\mathrm{Z}_{\text {eff }}\) for an electron in a 2 s orbital is greater than that for the 1 s orbital. (b) The \(Z_{\text {eff for the } 2 p \text { and } 2 s \text { orbitals is the same. }}\) (c) More energy is required to remove an electron from a 2 s orbital than from the \(2 p\) orbital. (d) The 2 s electron is less shielded than the \(2 p\) electron.

Describe how the ionization energies of the ions \(\mathrm{He}^{-}, \mathrm{Li}^{-}, \mathrm{Be}^{-}, \mathrm{B}^{-}, \mathrm{C}^{-}, \mathrm{N}^{-}, \mathrm{O}^{-},\) and \(\mathrm{F}^{-}\) vary with atomic number.

Describe how the ionization energies of the ions \(\mathrm{Be}^{+}, \mathrm{B}^{+}, \mathrm{C}^{+}, \mathrm{N}^{+}, \mathrm{O}^{+}, \mathrm{F}^{+}, \mathrm{Ne}^{+},\) and \(\mathrm{Na}^{+}\) vary with atomic number.