Question

Calculate the number of neutrons the following element contain and state the formula used.

${{}_9\mathrm{F}}^{19}$

Answer 1

• An atom of an element is represented as ${{}_{\mathrm{Z}}\mathrm{X}}^{\mathrm{A}}$
• Where Z is the atomic number, and A is the mass number of element X.
• Atomic number(Z)- The total number of protons in the nucleus of an atom gives us the atomic number of that atom.
• Mass number(A)- The number of protons and neutrons combine to give us the mass number of an atom.
• Any neutral atom has the same number of electrons as the number of protons.
• For a neutral atom Z=atomic number=number of protons=number of electrons.
• Number of neutrons=A-Z
• In ${{}_9\mathrm{F}}^{19}$, 9 is the atomic number, and 19 is the mass number of Fluorine.
• Hence, the Number of neutrons=A-Z= 19-9=10.