Question

What is the mass in \[grams\] of a single atom of \[chlorine\] ? (Atomic mass of \[chlorine\]= \[35.5\])

Answer 1

Hint: To answer the above question we need to find the number of moles of the substance. Molecular mass is expressed in a unified atomic mass unit which is equal to the mass of that given compound in \[1mole\] of the molecule.

Complete answer:
Molecular mass is given by dividing the mass of a sample compound by the amount of substance in that sample. It is the mass of \[1mole\] of the substance or equals the Avogadro’s number which is \[6.022 \times {10^{23}}\] particles expressed in grams.
Keeping this concept in mind we will solve the given question
Atomic mass of \[chlorine\]=\[35.5\]
This means that \[6.022 \times {10^{23}}\] atoms of \[chlorine\] have a mass of \[35.5\]\[grams\]
This can be summed up as
1 mole = Atomic mass of \[chlorine\]= Avogadro’s number
1 mole \[chlorine\]= \[35.5\]\[grams\]= \[6.022 \times {10^{23}}\]
For 1 \[chlorine\] atom = \[\dfrac{{35.5}}{{6.022 \times {{10}^{23}}}}\]
\[ = 5.89 \times {10^{ - 23}}g/atom\]
Thus the mass in \[grams\] of a single atom of \[chlorine\] \[ = 5.89 \times {10^{ - 23}}g/atom\]

Additional information: The term molecular mass, molar mass and molecular weight are used interchangeably. The molecular mass is more commonly used when referring to the mass of a single or specific well defined molecule and less commonly than molecular weight when referring to a weighted average sample. The molecular mass of small to medium size molecules, measured by mass spectroscopy, can be used to determine the composition of elements in the molecules.

Note:
Another way of determining the molecular mass is by adding the atomic masses of all the compounds. This is done by calculating the molar mass of a compound with multiple atoms and summing up all the atomic mass of the constituent atoms.