Question

What Is Atomic Mass And Average Atomic Mass?

Answer 1

Atomic mass

• Mass shown by one atom of an element is known as its atomic mass.
• The atomic mass unit is defined as 1/12th of the mass of a single carbon-12 atom taken in grams.
• 1 amu= $1.66\times {10}^{-24}$ g.
• Example: atomic mass of a Hydrogen atom is taken as 1 amu.

Average Atomic Mass

• The isotopic abundance is factored into the average atomic mass (relative to each other found in the Earth).
• Carbon-12, for example, is the most prevalent isotope of carbon, with a relative abundance of 98.89 percent.
• Carbon-13 and carbon-14 have atomic masses of 13.003 amu and 14.003 amu, respectively.
• Carbon has an average atomic mass of 12.011 amu.
• Average atomic mass is the average mass of the compounds present in it.

Average atomic mass =$f_1{M}_1+f_2{M}_2+\dots +f_n{M}_n$

Here, f represents the relative abundance of the isotope and M is the atomic mass of the isotope.

• It is used because its numerical value is equal to the element's molar mass.