Question

Calculate the number of electrons, protons and neutrons in 1 mole of $ ^{16}{O^{ - 2}} $ ions.

Answer 1

Hint: An atom comprises a nucleus having neutrons and protons which are surrounded by electrons in orbits. Number of protons (atomic number i.e. ‘ $ Z $ ’) can be considered to be equal to the total number of electrons in a neutral atom. The summation of the number of neutrons and number of protons equals the mass number of an atom (denoted as’ $ M $ ’). Thus, the number of neutrons = $ M - Z $ .

Complete step by step solution:
 In the given question, we know the value of mass number ( $ M $ ) of the atom i.e. $ ^{16}{O^{ - 2}} $ which is mentioned below:
 $ \begin{gathered}
  M = 16 \\
  Z = ? \\
\end{gathered} $
We know that the atomic number of Oxygen is equal to 8 while the mass number of Oxygen is 16. We already know that:
 $ Mass{\text{ }}number = number{\text{ }}of{\text{ }}protons + number{\text{ }}of{\text{ }}neutrons $
Thus, number of neutrons in oxygen atom will be $ 16 - 8 = 8 $
As atomic number is equal to the number of protons thus:
 $ number{\text{ }}of{\text{ }}protons = 8 $
In case of neutral atom, number of electrons is equal to the number of protons so:
 $ number{\text{ }}of{\text{ electr}}ons = 8 $
Now, in case of $ ^{16}{O^{ - 2}} $ , it indicates that the oxygen atom might have gained 2 electrons from some other atom in order to become an anion i.e. $ ^{16}{O^{ - 2}} $ . In this case:
 $ number{\text{ }}of{\text{ electr}}ons = 8 + 2 = 10 $
We know that:
 $ 1mole = 6.022 \times {10^{23}}ions $
Total number of electrons in 1 mole of $ ^{16}{O^{ - 2}} $ $ = 10 \times 6.022 \times {10^{23}} = 6.022 \times {10^{24}} $ . Similarly:
Total number of protons in 1 mole of $ ^{16}{O^{ - 2}} $ $ = 8 \times 6.022 \times {10^{23}} = 48.176 \times {10^{23}} $
Total number of neutrons in 1 mole of $ ^{16}{O^{ - 2}} $ $ = 8 \times 6.022 \times {10^{23}} = 48.176 \times {10^{23}} $

Note:
Each atom of a given element has the similar number of protons while atoms of distinct elements possess distinct numbers of protons. An atom consists of the same number of protons as well as electrons. As protons as well as electrons possess equal and opposite electrical charges, atoms have no overall electrical charge (i.e. neutral).