Q12E - Chemistry (OpenStax)

Question

Write the symbol for each of the following ions: (a) the ion with a \(3 + \) charge, \(28\) electrons, and a mass number of \(71\)(b) the ion with \(36\) electrons, \(35\) protons, and \(45\) neutrons (c) the ion with \(86\) electrons, \(142\) neutrons, and a \(4 + \) charge (d) the ion with a \(2 + \) charge, atomic number \(38,\) and mass number \(87\) 

Step-by-Step Solution

Answer

The symbols are:

a. \({}_{31}^{71}G{a^{3 + }}\)

b. \({}_{35}^{80}B{r^{ - 1}}\)

c. \({}_{90}^{232}T{h^{4 + }}\)

d. \({}_{38}^{87}S{r^{2 + }}\)

Step 1: Determine the symbol.

It is given that the ion has a \(3 + \) charge, \(28\)electrons, and a mass number of \(71\).

The atomic number of an atom \( = \) Number electrons \( + \)atomic charge

                                                     \(\begin{aligned}{\underline{\phantom{xx}}}& = 28 + 3\\ &= 31\\ &= Ga\left( {{\rm{gallium}}} \right)\end{aligned}\)

Therefore, the symbol of the ion: \({}_{31}^{71}G{a^{3 + }}\)

Step 2: Determine the symbol

It is given that the ion has \(36\) electrons, \(35\) protons, and \(45\) neutrons.

The atom with number of protons \( = \)atomic number

                                                       \(\begin{aligned}{\underline{\phantom{xx}}}& = 35\\ &= Br{\rm{(Bromine)}}\end{aligned}\)

Mass number of bromine\((Br) = \) Number of neutrons \( + \)Number of protons

                                               \(\begin{aligned}{\underline{\phantom{xx}}}& = 35 + 45\\ &= 80\end{aligned}\)

The charge on bromine \((Br) = \) Number of protons \( - \)Number of electrons

                                               \(\begin{aligned}{\underline{\phantom{xx}}}& = 35 - 36\\ &=  - 1\end{aligned}\)

Therefore, the symbol of the ion: \({}_{35}^{80}B{r^{ - 1}}\)

Step 3: Determine the symbol.

It is given that the ion has \(86\) electrons, \(142\) neutrons, and a \(4 + \)charge.

The atomic number \( = \) Electrons \( + \) Charge on atom

\(\begin{aligned}{\underline{\phantom{xx}}}& = 86 + 4\\ &= 90\\ &= Th{\rm{(Thorium)}}\end{aligned}\)

Mass number of Thorium\((Th) = \) Number of neutrons \( + \)Number of protons

\(\begin{aligned}{\underline{\phantom{xx}}}& = 90 + 142\\ &= 232\end{aligned}\)

Therefore, the symbol of the ion: \({}_{90}^{232}T{h^{4 + }}\)

Step 4: Determine the symbol.

It is given that the ion has a \(2 + \) charge, atomic number \(38\), and mass number \(87\).

The atom with the atomic number \(38\) and mass number \(87\) is strontium\(\left( {Sr} \right)\).

Therefore, the symbol of the ion: \({}_{38}^{87}S{r^{2 + }}\)