Question

18
ar
argon
39.95
protons:
neutrons:
electrons:

Explanation:

Step1: Determine number of protons

The atomic number is 18, so number of protons = 18.

Step2: Calculate number of neutrons

Atomic mass ≈ 39.95, rounded to 40. Neutrons = Atomic mass - Protons. So neutrons = 40 - 18 = 22.

Step3: Determine number of electrons

In a neutral atom, number of electrons = number of protons. So electrons = 18.

Answer:

Protons: 18
Neutrons: 22
Electrons: 18