Question

Calculate the number atoms in 0.2 mole of sodium (Na).

Answer 1

Hint: We know that one mole of all chemicals contains Avogadro number of atoms in it.
One mole of a chemical = Avogadro number of atoms.
The symbol to denote Avogadro number is ${{N}_{A}}$ .
The value of Avogadro number = $6.023\times {{10}^{23}}atoms$

Complete answer:
- In the question it is given that we have to calculate the number of atoms in 0.2 mole of sodium.
- The chemical symbol used to denote the sodium is Na and sodium belongs to s-block.
- We know that 1 mole of sodium contains Avogadro number of atoms.
One mole of sodium = $6.023\times {{10}^{23}}atoms$
- But we have to find the number of atoms in 0.2 mole of sodium.
- Then, 0.2 mole of sodium
\[\begin{align}
  & =6.023\times {{10}^{23}}atoms\times 0.2 \\
 & =12.046\times {{10}^{23}}atoms \\
\end{align}\]
- Therefore 0.2 moles of sodium (Na) contains $12.046\times {{10}^{23}}atoms$ in it.

Additional information:
- The term Avogadro number was introduced by Perrin, a French physicist.
- Avogadro number is the proportionality factor that gives the information about the number of atoms in the given amount of sample or chemical.
- Sometimes Avogadro numbers are called Avogadro constant.

Note:
Avogadro number is the ratio of charge on a mole of electrons to the charge on a single electron and we can represent it in the form of formula as mentioned below.
Avogadro number = $\dfrac{\text{Charge on one mole of electrons}}{\text{charge on a single electron}}$
There is no relation between molecular weight of the substance and Avogadro number. Avogadro number is going to depend on the number of moles of the chemical.