Question

If the mass number of an element is 31 and it contains 15 electrons, then what is the number of neutrons in it? What is its atomic number?

Answer 1

• The number of electrons present in the given element = 15
• The number of electrons in the element equals its number of protons.
• Hence the number of protons of the given element = 15
• The number of protons of an element equals its atomic number.
• Hence atomic of an element(Z) = 15
• The mass number of a given element = 31
• Therefore the number of neutrons = Mass number - Atomic number = 31 - 15 = 16