Answer :
- Determine the number of protons from the atomic number: 79.
- Calculate the number of neutrons by subtracting the atomic number from the mass number: $197 - 79 = 118$.
- Find the number of electrons by accounting for the ion's charge: $79 - 3 = 76$.
- The ion ${ }_{79}^{197}Au^{3+}$ has $\boxed{79 p, 118 n, 76 e}$.
### Explanation
1. Understanding the Ion Notation
We are asked to determine the number of protons, neutrons, and electrons in the given gold ion, ${ }_{79}^{197}Au^{3+}$. Let's break down what each part of this notation tells us.
2. Determining the Number of Protons
The number 79 at the bottom left is the atomic number. The atomic number defines the element and is equal to the number of protons in the nucleus. Therefore, gold (Au) always has 79 protons.
3. Calculating the Number of Neutrons
The number 197 at the top left is the mass number. The mass number is the total number of protons and neutrons in the nucleus. To find the number of neutrons, we subtract the atomic number (number of protons) from the mass number: $197 - 79 = 118$. So, there are 118 neutrons.
4. Finding the Number of Electrons
The $3+$ superscript indicates the ion's charge. A neutral gold atom has 79 electrons (equal to the number of protons). A $3+$ charge means the ion has lost 3 electrons. Therefore, the number of electrons is $79 - 3 = 76$.
5. Final Summary
In summary, the ${ }_{79}^{197}Au^{3+}$ ion has 79 protons, 118 neutrons, and 76 electrons.
6. The Answer
Therefore, the correct answer is: $79 p ^{\circ}, 118 n ^{\circ}, 76 e ^{-}$.
### Examples
Understanding the composition of ions is crucial in various fields. For example, in nuclear medicine, radioactive isotopes like gold-198 (¹⁹⁸Au) are used for cancer therapy. Knowing the number of protons, neutrons, and electrons helps scientists predict the isotope's stability and decay pathways, ensuring safe and effective treatment. Similarly, in materials science, the ionic state of elements affects the properties of compounds, influencing their conductivity and reactivity.
- Calculate the number of neutrons by subtracting the atomic number from the mass number: $197 - 79 = 118$.
- Find the number of electrons by accounting for the ion's charge: $79 - 3 = 76$.
- The ion ${ }_{79}^{197}Au^{3+}$ has $\boxed{79 p, 118 n, 76 e}$.
### Explanation
1. Understanding the Ion Notation
We are asked to determine the number of protons, neutrons, and electrons in the given gold ion, ${ }_{79}^{197}Au^{3+}$. Let's break down what each part of this notation tells us.
2. Determining the Number of Protons
The number 79 at the bottom left is the atomic number. The atomic number defines the element and is equal to the number of protons in the nucleus. Therefore, gold (Au) always has 79 protons.
3. Calculating the Number of Neutrons
The number 197 at the top left is the mass number. The mass number is the total number of protons and neutrons in the nucleus. To find the number of neutrons, we subtract the atomic number (number of protons) from the mass number: $197 - 79 = 118$. So, there are 118 neutrons.
4. Finding the Number of Electrons
The $3+$ superscript indicates the ion's charge. A neutral gold atom has 79 electrons (equal to the number of protons). A $3+$ charge means the ion has lost 3 electrons. Therefore, the number of electrons is $79 - 3 = 76$.
5. Final Summary
In summary, the ${ }_{79}^{197}Au^{3+}$ ion has 79 protons, 118 neutrons, and 76 electrons.
6. The Answer
Therefore, the correct answer is: $79 p ^{\circ}, 118 n ^{\circ}, 76 e ^{-}$.
### Examples
Understanding the composition of ions is crucial in various fields. For example, in nuclear medicine, radioactive isotopes like gold-198 (¹⁹⁸Au) are used for cancer therapy. Knowing the number of protons, neutrons, and electrons helps scientists predict the isotope's stability and decay pathways, ensuring safe and effective treatment. Similarly, in materials science, the ionic state of elements affects the properties of compounds, influencing their conductivity and reactivity.
