Question

How many protons are in the nucleus of an atom that has an atomic number of $23$ and a mass number of $51$?

Answer 1

We know that an atom defines a chemical element uniquely. It consists of a nucleus which is generally surrounded by one or more than one electrons which are negatively charged particles. The nucleus has an overall positive charge. It consists of neutrons and protons which are heavy particles. The neutrons do not have any charge but the protons are positively charged particles. So, the nucleus has an overall positive charge.

Complete answer:
The atomic number of an element gives information about the number of protons present in the nucleus of an atom. It is also an identity of the chemical element. The atomic number of a chemical element is generally the number of positive particles i.e. the number of protons that are present in the nucleus. The atom having an atomic number of $23$ and a mass number of $51$ is vanadium. We can find the element corresponding to an atomic number by looking at the periodic table. The number of protons present in vanadium is equal to $23$ as its atomic number is equal to $23$.

Note:
Atomic number and mass number help in determining the number of protons, electrons and neutrons of a chemical element. The mass number of a chemical element is the sum of the number of protons and number of neutrons. To know the number of neutrons, we have to subtract the atomic number from the mass number.