To determine the number of nucleons, let's break down the given information of the atom [tex]\(_{18}^{40}Ar\)[/tex]:
1. Identify the Atomic Number and Mass Number:
- The atomic number (denoted as the subscript) is 18.
- The mass number (denoted as the superscript) is 40.
2. Understand What Each Number Represents:
- The atomic number (18) represents the number of protons in the nucleus.
- The mass number (40) represents the total number of nucleons (protons + neutrons) in the nucleus.
3. Calculate the Number of Neutrons:
- The number of neutrons can be calculated by subtracting the atomic number from the mass number:
[tex]\[
\text{Number of neutrons} = \text{Mass number} - \text{Atomic number} = 40 - 18 = 22
\][/tex]
4. Summarize the Values:
- Protons: 18 (given by the atomic number)
- Neutrons: 22 (calculated above)
- Nucleons: 40 (mass number)
Given these calculations, the total number of nucleons (protons + neutrons) in the nucleus of an [tex]\(_{18}^{40}Ar\)[/tex] atom is 40.
Reviewing the given options:
- Option A) 18 electrons: This is incorrect because it refers to electrons, not nucleons.
- Option B) 18 protons: This is correct in terms of proton count, but not what the question asks for.
- Option C) 18 neutrons: This is incorrect because there are 22 neutrons.
- Option D) 18 nucleons: This is incorrect because there are 40 nucleons.
Therefore, the correct answer is not listed among the provided choices. The total number of nucleons is 40. The values provided in the options do not accurately represent the total number of nucleons.
