Question

How many protons are found in the nucleus of one atom of gold?

Answer 1

Hint For calculating the number of protons in an atom we have to know about the atomic number of that atom, because Atomic number (${\text{Z}}$) of an atom is always equal to the number of protons present inside the nucleus or number of electrons present outside the nucleus in the orbitals.

Complete step by step solution: Gold is situated in the 5d series of the d – block in the periodic table and denoted by the symbol as ${}_{{\text{197}}}^{{\text{79}}}{\text{Au}}$.
-Upper quantity in ${}_{{\text{197}}}^{{\text{79}}}{\text{Au}}$ describes the atomic number (${\text{Z}}$) of the gold atom.
-Lower quantity in ${}_{{\text{197}}}^{{\text{79}}}{\text{Au}}$ describes the atomic mass (${\text{A}}$) of the gold atom.
-As we know that relation between the atomic number and number of protons present inside the nucleus is represented as follow:
Atomic Number (${\text{Z}}$) = No. of protons = No. of electrons
-From the denotation of gold it is clear that the atomic number of gold is $79$, so the number of protons in the gold atom is also $79$.
Hence, in the nucleus of one atom of gold $79$ protons are found.

Additional information:
Number of protons present inside the nucleus in an atom is also calculated by knowing the atomic mass (${\text{A}}$) and number of neutrons as follow:
Atomic mass (${\text{A}}$) = No. of protons + No. of neutrons.

Note: Here some of you may get confused on calculating the number of protons if atomic mass (${\text{A}}$) and atomic number (${\text{Z}}$) both are given, then in this condition always keep in mind that atomic number is equal to number of protons.