What is the mass number of an atom of potassium that has 18 neutrons?

1 Answer
Jul 7, 2016


Mass Number of Potassium = 37amu.


The mass number of an element is determined by adding the number of protons and neutrons in the atom.

Potassium is atomic number 19 on the periodic table.

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The atomic number is equal to the number of protons.

Atomic number 19 = 19 protons.
We are told in the question 18 neutrons

Mass number = Protons + Neutrons

Mass number #= 19 + 18#

Mass Number of Potassium = 37amu.