Chapter 6

Predict the ground-state electron configuration for each of the following ions: (a) \(\mathrm{Ra}^{2+}\) (b) \(\mathrm{Ni}^{2+}\) (c) \(\mathrm{N}^{3-}\)

Which of the following sets of ions are isoelectronic? (a) \(\mathrm{F}^{-}, \mathrm{Cl}^{-}, \mathrm{Br}^{-}\) (b) \(\mathrm{Ti}^{4+}, \mathrm{Ca}^{2+}, \mathrm{Cl}^{-}\) (c) \(\mathrm{Na}^{+}, \mathrm{Mg}^{2+}, \mathrm{Al}^{3+}\)

Which atom or ion in each of the following pairs would you expect to be larger? (a) \(\mathrm{O}\) or \(\mathrm{O}^{2-}\) (b) Fe or \(\mathrm{Fe}^{3+}\) (c) \(\mathrm{H}\) or \(\mathrm{H}^{-}\)

(a) Which has the larger third ionization energy, Be or \(\mathrm{N}\) ? (b) Which has the larger fourth ionization energy, Ga or Ge?

Why does manganese, atomic number 25 , have a less favorable \(E_{\text {ea }}\) than its neighbors on either side?

What noble-gas configurations are the following elements likely to adopt in reactions when they form ions? (a) \(\mathrm{Rb}\) (b) Ba (c) \(\mathrm{Ga}\) (d) \(\mathrm{F}\)

What are group 6 A elements likely to do when they form ions-gain electrons or lose them? How many? What will be the charge on the ion of a \(6 \mathrm{~A}\) element?

Calculate the net energy change in kilojoules per mole that takes place on formation of \(\mathrm{MgF}_{2}(s)\) from the elements: \(\mathrm{Mg}(s)+\mathrm{F}_{2}(g) \longrightarrow \mathrm{MgF}_{2}(s)\). The following information is needed: Heat of sublimation for \(\mathrm{Mg}(s)=147.7 \mathrm{~kJ} / \mathrm{mol}\) \(E_{\mathrm{ea}}\) for \(\mathrm{F}(\mathrm{g})=-328 \mathrm{~kJ} / \mathrm{mol}\) Bond dissociation energy for \(\mathrm{F}_{2}(g)=158 \mathrm{~kJ} / \mathrm{mol}\) \(E_{\mathrm{il}}\) for \(\mathrm{Mg}(\mathrm{g})=737.7 \mathrm{~kJ} / \mathrm{mol}\) Electrostatic interactions in \(\mathrm{MgF}_{2}(s)=-2957 \mathrm{~kJ} / \mathrm{mol} \quad E_{\mathrm{i} 2}\) for \(\mathrm{Mg}(g)=1450.7 \mathrm{~kJ} / \mathrm{mol}\)

Which substance in each of the following pairs has the larger lattice energy? (a) \(\mathrm{KCl}\) or \(\mathrm{RbCl}\) (b) \(\mathrm{CaF}_{2}\) or \(\mathrm{BaF}_{2}\) (c) \(\mathrm{CaO}\) or \(\mathrm{KI}\)

What structural features do ionic liquids have that prevent them from forming solids easily?

An ionic liquid consisting of a bulky amine cation and chloride anion has a melting point of \(41^{\circ} \mathrm{C}\). For a green chemistry solvent application, it is desirable to have a melting point below room temperature \(\left(25^{\circ} \mathrm{C}\right)\) so energy is not required to heat the compound. The melting point of the ionic liquid can be altered by replacing chloride with a different anion. The anion possibilities are: \(\mathrm{F}^{-}, \mathrm{Se}^{2-}, \mathrm{O}^{2-}\), and \(\mathrm{Br}^{-}\) (a) Write the electron configuration for each of these ions. (b) Which ions are isoelectronic? (c) Which ion is the best choice for replacing the chloride ion to make an ionic liquid with a lower melting temperature?

Where on the periodic table would you find the element that has an ion with each of the following electron configurations? Identify each ion. (a) \(3+\) ion: \(1 s^{2} 2 s^{2} 2 p^{6}\) (b) \(3+\) ion: \([\mathrm{Ar}] 3 d^{3}\) (c) \(2+\) ion: \([\mathrm{Kr}] 5 s^{2} 4 d^{10}\) (d) \(1+\) ion: \([\mathrm{Kr}] 4 d^{10}\)

What is the difference between a covalent bond and an ionic bond?

Characterize bonds between the two atoms as covalent or ionic. (a) \(\mathrm{Cl}\) and \(\mathrm{F}\) (b) \(\mathrm{Rb}\) and \(\mathrm{F}\) (c) \(\mathrm{Na}\) and \(\mathrm{S}\) (d) \(\mathrm{N}\) and \(\mathrm{S}\)

What is the difference between a molecule and an ion?

Label the following species as molecules or ions. (a) \(\mathrm{NO}_{3}^{-}\) (b) \(\mathrm{NH}_{4}^{+}\) (c) \(\mathrm{NO}_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{CO}_{2}^{-}\)

How many protons and electrons are in each of the following ions? (a) \(\mathrm{Be}^{2+}\) (b) \(\mathrm{Rb}^{+}\) (c) \(\mathrm{Se}^{2-}\) (d) \(\mathrm{Au}^{3+}\)

What is the identity of the element \(\mathrm{X}\) in the following ions? (a) \(\mathrm{X}^{2+}\), a cation that has 36 electrons (b) \(\mathrm{X}\), an anion that has 36 electrons

What are the likely ground-state electron configurations of the following cations? (a) \(\mathrm{La}^{3+}\) (b) \(\mathrm{Ag}^{+}\) (c) \(\mathrm{Sn}^{2+}\)

What are the likely ground-state electron configurations of the following anions? (a) \(\mathrm{Se}^{2-}\) (b) \(\mathrm{N}^{3-}\)

What is the electron configuration of \(\mathrm{Ca}^{2+}\) ? What is the electron configuration of \(\mathrm{Ti}^{2+}\) ?

Identify the element whose \(2+\) ion has the ground-state electron configuration \([\mathrm{Ar}] 3 d^{10}\).

What doubly positive ion has the following ground-state electron configuration? \(1 s^{2} 2 s^{2} 2 p^{6}\) .

What tripositive ion has the electron configuration \([\mathrm{Kr}] 4 d^{3} ?\) What neutral atom has the electron configuration \([\mathrm{Kr}] 5 s^{2} 4 d^{2} ?\)

There are two elements in the transition-metal series Sc through Zn that have four unpaired electrons in their \(2+\) ions. Identify them.

Which element in the transition-metal series Sc through \(\mathrm{Zn}\) has five unpaired electrons in its \(+3\) ion?

Which atom or ion in the following pairs would you expect to be larger? (a) S or \(\mathrm{S}^{2-}\) (b) \(\mathrm{Ca}\) or \(\mathrm{Ca}^{2+}\) (c) \(\mathrm{O}^{-}\) or \(\mathrm{O}^{2}\)

Which atom or ion in the following pairs would you expect to be larger? (a) \(\mathrm{Rb}\) or \(\mathrm{Rb}^{+}\) (b) \(\mathrm{N}\) or \(\mathrm{N}^{3-}\) (c) \(\mathrm{Cr}^{3+}\) or \(\mathrm{Cr}^{6+}\)

Order the following ions from smallest to largest. \(\mathrm{Sr}^{2+}, \mathrm{Se}^{2-}\), \(\mathrm{Br}^{-}, \mathrm{Rb}^{+}\)

Order the following ions from smallest to largest. \(\mathrm{Mg}^{2+}, \mathrm{O}^{2-}\), \(\mathrm{F}^{-}, \mathrm{Na}^{+}\)

Which element in the periodic table has the smallest ionization energy? Which has the largest?

Which element in each of the following sets has the smallest first ionization energy, and which has the largest? (a) \(\mathrm{Li}, \mathrm{Ba}, \mathrm{K}\) (b) \(\mathrm{B}, \mathrm{Be}, \mathrm{Cl}\) (c) \(\mathrm{Ca}, \mathrm{C}, \mathrm{Cl}\)

Order the elements in each set from the smallest to largest first ionization energy. (a) \(\mathrm{Na}, \mathrm{I}, \mathrm{P}\) (b) \(\mathrm{P}, \mathrm{Sr}, \mathrm{Mg}\) (c) \(\mathrm{Ca}, \mathrm{Cs}, \mathrm{Se}\)

(a) Which has the smaller second ionization energy, \(\mathrm{K}\) or \(\mathrm{Ca}\) ? (b) Which has the larger third ionization energy, Ga or Ca?

(a) Which has the smaller fourth ionization energy, Sn or Sb? (b) Which has the larger sixth ionization energy, Se or \(\mathrm{Br}\) ?

The first four ionization energies in \(\mathrm{kJ} / \mathrm{mol}\) of a certain secondrow element are \(801,2427,3660\), and \(25,025 .\) What is the likely identity of the element?

The first four ionization energies in \(\mathrm{kJ} / \mathrm{mol}\) of a certain secondrow element are \(900,1757,14,849\), and \(21,007 .\) What is the likely identity of the element?

What is the relationship between the electron affinity of a singly charged cation such as \(\mathrm{Na}^{+}\) and the ionization energy of the neutral atom?

What is the relationship between the ionization energy of a singly charged anion such as \(\mathrm{Cl}^{-}\) and the electron affinity of the neutral atom?

Which has the more negative electron affinity, \(\mathrm{Na}^{+}\) or Na? Na' or Cl?

Why is energy usually released when an electron is added to a neutral atom but absorbed when an electron is removed from a neutral atom?

Why does ionization energy increase regularly across the periodic table from group \(1 \mathrm{~A}\) to group \(8 \mathrm{~A}\), whereas electron affinity increases irregularly from group \(1 \mathrm{~A}\) to group \(7 \mathrm{~A}\) and then falls dramatically for group \(8 \mathrm{~A} ?\)

No element has a negative second electron affinity. That is, the process \(\mathrm{A}^{-}(\mathrm{g})+\mathrm{e}^{-} \longrightarrow \mathrm{A}^{2-}(g)\) is unfavorable for every ele- ment. Suggest a reason.

What noble-gas configurations and charge are the following elements likely to attain in reactions in which they form ions? (a) \(\mathrm{N}\) (b) \(\mathrm{Ca}\) (c) \(\mathrm{S}\) (d) \(\overline{B r}\)

Each of the following pairs of elements will react to form a binary ionic compound. Write the formula of each compound formed, and give its name. (a) Magnesium and chlorine (b) Calcium and oxygen (c) Lithium and nitrogen (d) Aluminum and oxygen

Element X reacts with element \(\mathrm{Y}\) to give a product containing \(\mathrm{X}^{3+}\) ions and \(\mathrm{Y}^{2-}\) ions. (a) Is element \(\mathrm{X}\) likely to be a metal or a nonmetal? Explain. (b) Is element \(\mathrm{Y}\) likely to be a metal or a nonmetal? Explain. (c) What is the formula of the product? (d) In what groups of the periodic table are elements \(\mathrm{X}\) and \(\mathrm{Y}\) likely to be found?

Element X reacts with element \(\mathrm{Y}\) to give a product containing \(\mathrm{X}^{3+}\) ions and \(\mathrm{Y}^{2-}\) ions. (a) Is element \(X\) likely to be a metal or a nonmetal? Explain. (b) Is element \(Y\) likely to be a metal or a nonmetal? Explain. (c) What is the formula of the product? (d) In what groups of the periodic table are elements \(\mathrm{X}\) and \(\mathrm{Y}\) likely to be found?

Order the following compounds according to their expected lattice energies: \(\mathrm{LiCl}, \mathrm{KCl}, \mathrm{KBr}, \mathrm{MgCl}_{2}\).

Order the following compounds according to their expected lattice energies: \(\mathrm{AlBr}_{3}, \mathrm{MgBr}_{2}, \mathrm{LiBr}, \mathrm{CaO}\).

Calculate the energy change in kilojoules per mole when lithium atoms lose an electron to bromine atoms to form isolated \(\mathrm{Li}^{+}\) and \(\mathrm{Br}^{-}\) ions. [The \(E_{\mathrm{i}}\) for \(\mathrm{Li}(g)\) is \(520 \mathrm{~kJ} / \mathrm{mol}\); the \(E_{\text {ea }}\) for \(\mathrm{Br}(\mathrm{g})\) is \(-325 \mathrm{~kJ} / \mathrm{mol} .]\)