The mass no of argon is 39.948
Argon is a non metal element. Atomic mass of it is 39.94.
There are three natural isotopes.
Argon's atomic number is 18, which means it has 18 protons in its nucleus.
Argon is very unreactive as it is a noble gas. Its common oxidation number is zero.
Ar
Argon atoms have 18 protons which is similar to the number of electrons.
It is 87.3 K.
Helium, Xenon, Neon, Krypton, and Radon.
For most people there is absolutely no reason to buy any argon in their lifetimes.
The mass number of Am-241 is 241; each isotope has another mass number.
Atomic mass is the number of protons in an atom mass number is the number of protons plus neutrons in an atom the number of neutrons would equal the mass number minus the atomic number.
37Ar is a synthetic isotope. It decays, through electron capture, into 37Cl, and this decay would has a half-life of 35 days. That is, half of any given mass of 37Ar would have decayed into 37Cl in 35 days.