Question

How much protons, electrons and neutrons does an atom with atomic number $50$ and mass number $125$ contain?

Answer 1

Hint : Carbon-14 is an isotope of carbon. Isotopes have the same atomic number but their atomic masses are different from each other. Number of electrons and protons present in the element is always equal to the atomic number of the element.

Complete Step By Step Answer:
We know that atoms are the smallest unit of matter. An atom is made up of three subatomic particles: the proton, the neutron, and the electron. We should note that, nucleus is made up of protons and neutrons. Neutrons are dense and positively charged atoms.
The negatively charged electrons can be found around the nucleus in an electron cloud. The number of protons found in the nucleus equals the number of electrons that surround it, which is also equal to the atomic number of the corresponding element in the periodic table. The atomic mass of an element in a periodic table is equal to the sum of the number of protons and the number of neutrons.
So, we ignore the mass of the electron and state that the entire atomic mass of an atom resides in its nucleus, which consists of protons and neutrons.
Therefore, mass number $=$ mass of total neutrons present in the atom $+$ mass of total protons present in the atom.
$125=x(1)+50(1)$ as number of protons $=50.$
$x=125-50$
$\Rightarrow x=75$
Therefore, protons $=50$ ; electrons $=50$ ; neutrons $=75$ .

Note :
Note that do not get confused between isotopes, isobars and isotones. Isotopes have the same number of protons but their atomic masses are different and we know that, nucleus of an atom contains protons and neutrons and we also know that the entire mass of an atom is in the nucleus.