Question

Calculate number of valence electrons and non-valence electrons in 5.6 ml of $S{{O}_{2}}$ gas.

Answer 1

From electronic configuration of the elements we can calculate the total number of electrons present in them.
The electronic configuration of Sulphur is $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{4}}$
The electronic configuration of Oxygen is $1{{s}^{2}}2{{s}^{2}}2{{p}^{4}}$

Complete Solution :
- In the question it is asked to calculate the number of valence electrons and non-valence electrons in 5.6 ml of $S{{O}_{2}}$ gas.
- Before going to calculate the number of valence and non-valence electrons, we should calculate the numbers of molecules present in 5.6 ml of $S{{O}_{2}}$ gas.
- Therefore the formula to calculate the number of molecules in 5.6 ml of $S{{O}_{2}}$ gas is as follows.
Number of molecules = (number of moles) (Avogadro number)

& =\frac{5.6}{22400}\times 6.023\times {{10}^{23}} \\\ & =1.50575\times {{10}^{20}}molecules \\\ \end{aligned}$$ \- Means 5.6 ml of $S{{O}_{2}}$ gas at STP contains $1.50575\times {{10}^{20}} molecules$ . \- Now coming to the concept of valence and non-valence electrons present in $S{{O}_{2}}$. -Total number of electrons in one $S{{O}_{2}}$ molecule = 16 + 8 + 8 = 32. \- Number of valence electrons present in Sulphur = 6 \- Number of valence electrons present in Oxygen = 6 \- So, the total number of valence electrons in one $S{{O}_{2}}$ molecule is = 6 + 6 + 6 = 18. \- So, the number of non-valence electrons in one $S{{O}_{2}}$ molecule is = 32 - 18 = 14. \- Now we have to calculate the number of valence and non-valence electrons in $1.50575\times {{10}^{20}} molecules$ . \- The number of valence electrons in $1.50575\times {{10}^{20}}molecules$ of sulphur dioxide is $$\begin{aligned} & =1.50575\times {{10}^{20}}\times 18 \\\ & =27.1035\times {{10}^{20}} \\\ & =2.71035\times {{10}^{21}} \\\ \end{aligned}$$ \- The number of non-valence electrons in $1.50575\times {{10}^{20}} molecules$ of sulphur dioxide is $$\begin{aligned} & = 1.50575\times {{10}^{20}}\times 14 \\\ & = 21.0805\times {{10}^{20}} \\\ & = 2.10805\times {{10}^{21}} \\\ \end{aligned}$$ **Note:** We are not supposed to calculate the number of valence and non-valence electrons in one sulphur dioxide molecule, we are supposed to calculate the number of valence and non-valence electrons in 5.6 ml of sulphur dioxide.