Give the formula of a negative ion that would have the same number of electrons as each of the following positive ions. a. $\mathrm{K}^{+}$ b. $\mathrm{Mg}^{2+}$ c. $\mathrm{Sr}^{2+}$ d. $\mathrm{Cs}^{+}$

In an aqueous solution, which substance yields hydrogen ions as the only positive ion? (1) $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$, (2) $\mathrm{CH}_{3} \mathrm{COOH}$, (3) KH, (4) KOH.

Suppose that we have $2.10 \times 10^\pi$ doubly charged positive ions per cubic centimeter, all moving north with a speed of $1.40 \times 10^5 \mathrm{~m} / \mathrm{s}$. (a) Calculate the current density, in magnitude and direction. (b) Can you calculate the total current in this ion beam? If not, what additional information is needed?

Potassium ions $\left(\mathrm{K}^{+}\right)$have a positive charge. What happens to a potassium atom's electrons when it becomes an ion?

Find the hydronium ion $\left[\mathrm{H}_3 \mathrm{O}^{+}\right]$concentration for the substance with the given p H. Beer, 4.8

Write the charge and complete ground-state electron configuration of the monatomic ion most likely to be formed by each:
(a) $\mathrm{Cl}$

Use inversion to turn the following statement into question.

Il fait mauvais aujourd’hui.

$(a)$ An oxygen-$16$ ion with a mass of $2.66 \times 10^{-26} \mathrm{~kg}$ travels at $5.0 \times 10^6 \mathrm{~m} / \mathrm{s}$ perpendicular to a $1.20 \mathrm{~T}$ magnetic field, which makes it move in a circular arc with a $0.231 \mathrm{~m}$ radius. What positive charge is on the ion? $(b)$ What is the ratio of this charge to the charge of an electron? $(c)$ Discuss why the ratio found in $(b)$ should be an integer.

Give the formula of a negative ion that would have the same number of electrons as each of the following positive ions. $\mathrm{Rb}^{+}$

Write the complete chemical formula (symbol and charge) for the positive ion present in each of the following ionic compounds.

a. KCl

b. CaS

c. $\text{MgF}_2$

d. $\text{Al}_2\text{S}_3$

How many electrons must an aluminum atom, Z=13, lose to attain a noble gas configuration? Write the symbol for the ion formed.

At $50 ^ { \circ } \mathrm { C }$ the ion-product constant for $H_2O$ has the value $K _ { w } = 5.48 \times 10 ^ { - 14 }$ Based on the change in $K_w$ with temperature, predict whether $\Delta H$ is positive, negative, or zero for the autoionization reaction of water: $2 \mathrm { H } _ { 2 } \mathrm { O } ( l ) \rightleftharpoons \mathrm { H } _ { 3 } \mathrm { O } ^ { + } ( a q ) + \mathrm { OH } ^ { - } ( a q )$

What doubly positive ion has the following ground-state electron configuration? $1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^{15}$

Find the hydronium ion $\left[\mathrm{H}_3 \mathrm{O}^{+}\right]$concentration for the substance with the given p H. Wine, 3.4