The number of neutrons in an atom having mass number 39 and atomic number 19 is ___________.
Atomic number: The total number of protons in the nucleus of an atom gives us the atomic number of that atom. It is represented by ''.
Atomic number = Number of protons
The atomic number given in the question is 19, so the number of protons is19.
Mass number: The number of protons and neutrons combine to give us the mass number of an atom. It is represented using the letter ‘.’
Mass number = number of protons + number of neutrons
Since the mass number given in the question is 39, it is the sum of both protons and neutrons.
Formula to calculate the number of neutrons = mass number (A) - atomic number (Z)
So, the number of neutrons=
Number of neutrons=
Therefore, the number of neutrons in an atom having mass number 39 and atomic number 19 is 20.