The masses of isotopes are not strictly the integral multiples of the mass of a hydrogen atom. Why?
Answers
To measure various objects, we use a gram or a kilogram as the standards. However, the mass of an atom is really small as compared to a kilogram. To give you a perspective, the mass of a carbon atom 12C, is 1.992647 × 10–26 kg. Imagine writing the mass of atoms in kilograms – not very convenient is it? Hence, Atomic Mass is expressed using different units. Let’s find more about the composition of a nucleus in the section below.
EXPLANATION:
One Atomic Mass unit (u) is defined as 1/12th of the mass of the carbon atom (12C). Therefore,
One Atomic Mass unit (u) is defined as 1/12th of the mass of the carbon atom (12C). Therefore,1u = (mass of one 12C atom)/12 = (1.992647 × 10–26)/12 = 1.660539 10–27 kg … (1)
One Atomic Mass unit (u) is defined as 1/12th of the mass of the carbon atom (12C). Therefore,1u = (mass of one 12C atom)/12 = (1.992647 × 10–26)/12 = 1.660539 10–27 kg … (1)Now, the atomic mass of different elements expressed in atomic units (u) is nearly equal to being integral multiples of the mass of a hydrogen atom. However, it is important to note that there are many exceptions to this rule.
One Atomic Mass unit (u) is defined as 1/12th of the mass of the carbon atom (12C). Therefore,1u = (mass of one 12C atom)/12 = (1.992647 × 10–26)/12 = 1.660539 10–27 kg … (1)Now, the atomic mass of different elements expressed in atomic units (u) is nearly equal to being integral multiples of the mass of a hydrogen atom. However, it is important to note that there are many exceptions to this rule.The next point is how do we measure atomic mass accurately? The answer is – by using a mass spectrometer. An interesting observation made by measuring atomic masses is that there are many atoms of the same element which have different masses but exhibit the same chemical properties. Such atoms are called ‘Isotopes’.