Question

Calculate the number of neutrons in the following element:

${}_1{}^3\mathrm{H}$

Answer 1

For any element X, mass number and atomic number is represented as ${}_{\mathrm{Atomic}\mathrm{number}}{}^{\mathrm{Mass}\mathrm{number}}\mathrm{X}$

$\mathrm{Number}\mathrm{of}\mathrm{neutrons}=\mathrm{Mass}\mathrm{number}-\mathrm{Number}\mathrm{of}\mathrm{protons}$

Step-1: Calculate the mass number of Hydrogen (H)

• For ${}_1{}^3\mathrm{H}$, Mass number = 3

Step-2: Calculate the number of protons

• Number of protons in an atom = Atomic number of that element
• From ${}_1{}^3\mathrm{H}$, Atomic number = 1 (Given)
• Therefore, Number of protons = 1

Step-3: Calculate the number of neutrons

• Substituting the values of mass number and number of protons in the above formula
• Number of neutrons = 3- 1 = 2
• Number of neutrons = 2