Chapter 45, Problem 18SP

To determine

The number of protons, neutrons, and electrons in the atom $\text{U}$.

Answer to Problem 18SP

Solution:

$92$, $143$, and $92$

Explanation of Solution

Given data:

The atom is represented as $\text{U}$.

Formula used:

An atom represented as $\text{X}$ represents the following data,

Here, $Z$ is the atomic number of the atom thatrepresents the number of protons in the atom. $A$ is the atomic mass thatrepresents the sum of the number of protons and neutrons in the atom. For a neutral atom, the number of electrons is equal to the number of protons.

The calculations for the atom $\text{X}$ are done by using the formula,

$\begin{array}{c}N=A-Z\\ n_p=Z\\ n_e=Z\end{array}$

Here, $n_p$, $n_e$, and $N$ indicate the number of protons, electrons, and neutrons in an atom, respectively.

Explanation:

Compare the atom $\text{U}$ with the standard form of an atom $\text{X}$.

$\begin{array}{l}A=235\\ Z=92\end{array}$

The number of protonsis equal to the atomic number. Hence, the number of protons in $\text{U}$ is $92$.

Observe the notation for the atom $\text{U}$, which indicates that the atom does not have any charge. Therefore, the number of protons is equal to the number of electrons. Hence, the number of electrons in $\text{U}$ is $92$.

Recall the formula to calculate the number of neutrons in the atom $\text{U}$.

$N=A-Z$

Substitute $\text{235}$ for $A$ and $92$ for Z

$\begin{array}{c}N=\text{235}-92\\ =143\end{array}$

The number of neutrons is $143$.

Conclusion:

Thenumber of protons, neutrons, and electrons in the atom $\text{U}$ are $92$, $143$, and $92$, respectively.