Question

How do you calculate the atomic mass of copper?

Answer 1

Atomic mass of any element depends on the nucleus of that element. So, Atomic mass of any element is calculated by the addition of the total number of protons and neutrons present in the nucleus of that element.

Complete Solution :
Atomic mass is denoted by the symbol ‘A’.
-In terms of atomic number, atomic mass of any element is calculated as follow:
${\text{A = Z + }}$ no. of neutrons
Where, A = Atomic number of elements.
-As we know that in periodic table copper is denoted as ${}_{29}^{63.5}Cu$, where upper quantity gives knowledge about atomic mass (${\text{A}}$) and lower quantity gives knowledge about atomic number (${\text{Z}}$).
-So, the atomic mass of copper is $63.5$ and atomic number is $29$.
-Atomic number is always equal to the numbers of electrons or protons present in the neutral element.
-From ${\text{A = Z + }}$ no. of neutrons, formula we can calculate the number of neutrons as follow:
No. of neutrons = ${\text{A - Z}}$
No. of neutrons = $63.5 - 29 = 34.5$
Or approx. No. of neutrons = $34$
Hence, the number of neutrons in the copper atom is $34$.

Additional information -
Copper has mainly two isotopes in nature which are denoted as ${}_{29}^{63}Cu$ and ${}_{29}^{65}Cu$. It means in ${}_{29}^{63}Cu$, no. of neutrons is $34$ and in ${}_{29}^{65}Cu$, no. of neutrons is $36$. Copper is the transition metal and present in the d-block of the periodic table.

Note: Here some of you may get confused in predicting the atomic mass and atomic number of by seeing the symbol of element and will do wrong calculation. So, always keep in mind high value quantity is the atomic mass and low value quantity is atomic number.