Question

18
Ar
Argon
39.948

Atomic number
atomic mass
# of protons
# of neutrons
# of electrons

Answer 1

For Argon (Ar), here are the details you provided along with additional information:

- **Atomic Number**: 18
- **Atomic Mass**: 39.948
- **Number of Protons**: 18 (the atomic number indicates the number of protons)
- **Number of Electrons**: 18 (in a neutral atom, the number of electrons equals the number of protons)
- **Number of Neutrons**: To find the number of neutrons, you can use the formula:

\[
\text{Number of Neutrons} = \text{Atomic Mass} - \text{Number of Protons}
\]

Since the atomic mass is approximately 39.948 and the number of protons is 18:

\[
\text{Number of Neutrons} \approx 39.948 - 18 \approx 21.948
\]

Neutrons are typically whole numbers, so rounding gives about 22 neutrons.

### Summary:
- **Atomic Number**: 18
- **Atomic Mass**: 39.948 (approximate)
- **Number of Protons**: 18
- **Number of Neutrons**: 22 (approximate)
- **Number of Electrons**: 18