Question

How many grams does an atom of hydrogen weigh?

Answer 1

Hint : Hydrogen is the first element in the periodic table with atomic number $\left( 1 \right)$ . Hydrogen is made up of one proton and one electron. Electronic configuration of hydrogen is $\left( {1{s^2}} \right)$ .Earlier chemists selected the hydrogen atom as the standard substance because it is the lightest atom of all the known atoms.

Complete Step By Step Answer:
Atomic mass of hydrogen is calculated with reference to the standard carbon atom $\left( {{C^{12}}} \right)$ .
In order to determine grams of hydrogen first we have to calculate the gram atomic mass of hydrogen.
Gram atomic mass of hydrogen = atomic mass of hydrogen expressed in term of gram
Gram atomic mass of hydrogen = $\left( x \right)g$
As we know weight of one mole of hydrogen atom is $1.008g$
We know that one mole of any element contains atoms equal to Avogadro number $\left( {6.022 \times {{10}^{24}}} \right)$ .
Therefore, one mole of hydrogen also contains $6.022 \times {10^{23}}$ atoms.
Which means that the weight of $6.022 \times {10^{23}}$ atoms of hydrogen is equal to $1.008g$ .
If weight of $6.022 \times {10^{23}}$ atoms $= 1.008g$ of hydrogen
Hence, weight of $1$ atom $= \dfrac{{1.008}}{{6.022 \times {{10}^{23}}}}$ $g$
After solving we get, $1$ atom $= \dfrac{{0.16736}}{{{{10}^{23}}}}$ $g$
$1$ atom $= 0.16736 \times {10^{ - 23}}$ $g$
Finally we get the weight of one atom of hydrogen $1.6736 \times {10^{ - 24}}g$ .

Note :
Currently $\left( {{C^{12}}} \right)$ isotope of carbon is used as a standard atom to determine the relative atomic mass of other atoms. Atomic mass is also expressed in terms of amu (atomic mass unit).
$1$ amu $= 1.66056 \times {10^{ - 24}}g$ .