What is the isotopic notation of an argon atom that has 22 neutrons?

1 Answer
anor277
Nov 4, 2017

Well, we got the element argon in whose nuclei BY DEFINITION there are 18 protons....so we gots #""^40Ar#..

Explanation:

Argon is defined by the presence of 18 massive, positively charged, particles in the element's nucleus, i.e. #"18 protons"#....and this contributes to the atomic mass....BUT we must also consider the mass of the neutrons in the determination of atomic mass.....

And different isotopes of the same element necessarily contain DIFFERENT numbers of #"neutrons"#...and so for #""^36Ar# there are 18 neutrons; for #""^38Ar# there are 20 neutrons; for #""^40Ar# there are 22 neutrons.

See here for the isotopic distribution of argon, which is mainly #""^40Ar#. How many electrons are there in each isotope with respect to the atom? Why so?

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