Question

If an atom of tin has a mass number of $118$ and an atomic number of $50$ , how many electrons does it have?

Answer 1

We already know that electrons are defined as the subatomic particles which orbits around the nucleus of an atom. They possess a negative charge which is much smaller than the nucleus of the atom. Atomic number helps in providing information about the number of protons which in turn helps in calculating the number of electrons in an element.

Complete step-by-step answer: Since we know that the atomic number given in the question is $50$ , hence the element can be identified as tin.
Now the atomic number, which is represented as $Z$, is equal to the number of protons in the nucleus which is denoted as ${n_p}$ .
Hence, $Z = {n_p} = 50$
Now, the number of protons is equal to the number of electrons in a neutral atom, which is represented as ${n_e}$ .
Therefore, ${n_p} = {n_e} = 50$
Hence we can say that the number of electrons present in an element whose atomic number is $50$ is said to be $50$ itself.

Note: The number of protons, neutrons, and electrons in an atom can be determined if the following rules are known,
A.The number of protons in the nucleus of the atom is equal to the atomic number (Z).
B.The number of electrons in a neutral atom is equal to the number of protons.
C.The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.
D.The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).