Question

How many grams does an atom of hydrogen weigh?

Answer 1

The mass of 1 mole of a compound is known as molar mass, the mole concept gives us an estimate about the number of atoms present in1 molar mass of a compound. Using the mole concept formula, we can then find the number of atoms in the molar mass of the compound. From there, we can calculate the weight of 1 atom of the substance given.
Formula used:
${\rm{Moles = }}\dfrac{{{\rm{weight}}}}{{{\rm{molar mass}}}}$ where molar mass is the mass of 1 mole of a compound.

Complete step by step answer:
The mole concept states that 1 mole of an atom or molecule consists of the same amount of particles in it. The number of particles in 1 mole is known as Avogadro’s number. It is equal to $6.023 \times {10^{23}}$ atoms or molecules. The mass of 1 mole is different for every compound. We know that the molar mass of hydrogen is ${\rm{1 g mo}}{{\rm{l}}^{{\rm{ - 1}}}}$. So, according to the mole concept, 1 mole of hydrogen consists of $6.023 \times {10^{23}}$ atoms. We can also write this as:
${\rm{1 mole hydrogen = 6}}{\rm{.023 \times 1}}{{\rm{0}}^{{\rm{23}}}}{\rm{ particles}}$
From the mole concept formula: ${\rm{1 mole of hydrogen = }}\dfrac{{{\rm{1 g}}}}{{{\rm{1 g mo}}{{\rm{l}}^{{\rm{ - 1}}}}}}$.
So, the weight of 1 mole of hydrogen is 1g.
$\Rightarrow {\rm{1g hydrogen = 6}}{\rm{.023 \times 1}}{{\rm{0}}^{{\rm{23}}}}{\rm{ particles}}$
$\Rightarrow {\rm{6}}{\rm{.023 \times 1}}{{\rm{0}}^{{\rm{23}}}}{\rm{ particles = 1g hydrogen}}$
From here, we can now calculate the mass of 1 atom of hydrogen:
$\Rightarrow {\rm{1 atom hydrogen = }}\dfrac{1}{{6.023 \times {{10}^{23}}}}g$
Solving this equation, we get:
${\rm{1 atom hydrogen = 0}}{\rm{.166}} \times {10^{ - 23}}g$

$\therefore$ The weight of 1 atom of hydrogen will be $1.66 \times {10^{ - 24}}g$.

Note:
The molar mass of a molecule will be different from the molar mass of an atom of the same element. For example, hydrogen as an atom has molar mass of ${\rm{1 g mo}}{{\rm{l}}^{ - 1}}$ while hydrogen molecule has a molar mass of ${\rm{2 g mo}}{{\rm{l}}^{ - 1}}$. This is because the hydrogen molecule is present as ${{\rm{H}}_{\rm{2}}}$. So, the mass is double the mass of an atom of hydrogen. While solving the question, we should be aware if the question contains an atom of the element or a molecule.