Question

Atomic number and mass number of an element are 15 and 31 respectively. Calculate the number of electrons, protons and neutrons.

Answer 1

Let X be the element.

${}_{15}{}^{31}\mathrm{X}$

• Atomic number of element X = 15
• Mass number of element X = 31
• Number of electrons = Atomic number = 15
• Number of protons = Atomic number = 15
• Number of neutrons = Mass number -Atomic number = 31-15 =16.