Question

How many neutrons will an atom of oxygen (atomic number 8) with an atomic mass of 16 have?

Answer 1

Hint: The atomic number of an element will be equal to the number of electrons or number of protons present in the atom. The nucleus consists of both the protons and neutrons.

Complete step by step answer:
So in the question, it asked how many neutrons will be there in the atom of oxygen and the atomic number and the mass number of oxygen is also given in the question.
From the time we are studying about the periodic table, we know that the elements in the periodic table are arranged according to the periodic law. The elements in the periodic table are arranged according to the increase in atomic number.
Now we have to know since in the question the atomic number and mass number of the oxygen is given there is some between these parameters with the number of protons, electrons and neutrons.
Let’s discuss briefly about atomic number and mass number of the elements.
Atomic number is the unique number for an element, which is the identity of an element and no two elements have the same atomic number. Atomic number tells us about the number of protons and electrons in the atom of concern.
The atomic number is equal to the number of electrons and number of protons present in the atoms.
Since we know that the atomic number of O is 8, therefore there are eight protons and eight electrons in O atom.
Now let’s discuss the atomic mass of an element. The weight of the nucleus accounts for the atomic mass of an electron. We know that the nucleus consists of both the neutrons and protons. The sum of the number of neutrons and the number of protons in an atom is equal to the atomic mass.
$Atomicmass=Numberof{p}^{+}s+Numberof{n}^{0}s.$
Here we know that the atomic mass is 16 and the number of protons are 8.Therefore, number of neutrons are,
$$\begin{gathered} Numberof{n}^{0}s=Atomicmass-Numberof{p}^{+}s. \\ Numberof{n}^{0}s=16-8=8(Numberof{n}^{0}s). \end{gathered}$$
So we got the final answer that the number of neutrons in an O atom is 8.

Note: The neutrons are chargeless species; they do not possess any charge, they only possess mass. The charge of the neutron is zero and the mass is slightly greater than that of proton which is $\text{1}\text{.67 }\times \text{ 1}{\text{0}}^{\text{-27}}\text{kg}$.Here all the subatomic particles are equal but in many it is not true, in sodium atom the atomic number is 11 and atomic mass is 23.Therefore the number of neutrons present in Na is 12.