Question

Mass of ${\text{1}}$ hydrogen atom is:
A. $1 \cdot 66 \times {10^{ - 24}}{\text{ g}}$
B. $1 \cdot 66 \times {10^{23}}{\text{ g}}$
C. $1 \cdot 66 \times {10^{ - 23}}{\text{ g}}$
D. $1 \cdot 66 \times {10^{24}}{\text{ g}}$

Answer 1

Hint: The mole is an international unit of measurement of substance in SI system, and one mole of any substance whether it is atoms, molecules or ions, is equal to $6 \cdot 02 \times {10^{23}}$ units of that substance.

Complete step by step answer:
-Hydrogen exists as a diatomic molecule in nature having formula ${H_2}$. So, to find the mass of ${\text{1}}$ hydrogen atom, we have to find how many hydrogen atoms there are in one mole of ${H_2}$. Then, the mass of the ${\text{1}}$ atom can be calculated.
-Atomic weight of one mole Hydrogen, ${H_2}$ is known, and is equal to ${\text{2 g mo}}{{\text{l}}^{ - 1}}$.
Since, ${\text{1}}$ mol of ${H_2}$ contains ${\text{2 mol}}$ of Hydrogen atoms.
So, the weight of ${\text{2 mol}}$ of Hydrogen atoms is ${\text{2 g}}$.
-We know that ${\text{1}}$ mol contains $6 \cdot 02 \times {10^{23}}$ atoms.
So, ${\text{2 mol}}$ Hydrogen atoms will contain $2 \times 6 \cdot 02 \times {10^{23}}$ atoms of Hydrogen.
-Now, the mass of $2 \times 6 \cdot 02 \times {10^{23}}$ Hydrogen atoms is equal to ${\text{2 g}}$.
Or, mass of ${\text{1}}$ Hydrogen atom is equal to $\dfrac{{{\text{2 }}}}{{2 \times 6 \cdot 02 \times {{10}^{23}}}}{\text{ g}}$
Or, mass of ${\text{1}}$ Hydrogen atom is equal to ${\text{1}} \cdot {\text{66}} \times {\text{1}}{{\text{0}}^{ - 24}}{\text{ g}}$.
Hence, option (a) $1 \cdot 66 \times {10^{ - 24}}{\text{ g}}$ is the correct answer of mass of ${\text{1}}$ hydrogen atom.

Additional Information: Mass number of any species is given by the sum of its protons and neutrons. Number of protons alone defines its atomic number. Relation of mass number and atomic number is seen in Isotopes. Isotopes are the species which have the same number of protons i.e. same atomic number but have different numbers of neutrons which give them different mass numbers. Hydrogen atoms have three isotopes, namely, protium, deuterium, and tritium.

Note: ${\text{1 mol}}$ anything is equal to the Avogadro’s Number, $6 \cdot 02 \times {10^{23}}$. To convert moles to atoms, multiply the given moles by the Avogadro’s Number, and to convert from atoms to moles, divide the given number of atoms by Avogadro’s Number.