The key difference between gram atomic mass and gram molecular mass is that the gram atomic mass gives the mass of an individual atom while the gram molecular mass gives the mass of a group of atoms.
Atomic mass and molecular mass (or molar mass) are very important regarding atoms and molecules. When we express these values in gram units, then it is gram atomic/molecular mass.
CONTENTS
1. Overview and Key Difference
2. What is Gram Atomic Mass
3. What is Gram Molecular Mass
4. Side by Side Comparison – Gram Atomic Mass vs Gram Molecular Mass in Tabular Form
5. Summary
What is Gram Atomic Mass?
Gram atomic mass is the atomic mass expressed with the unit “grams”. The value of this parameter is numerically equal to the atomic mass given by the unit “u”. This term is very closely related to the mass number. It actually means the same thing literally; however, in this case, the isotopic forms of each element are also counted. Elements can exist in various forms in nature. These different forms are generally known as isotopes, and they have the same identity as the most abundant/stable form of the element. Therefore, isotopes have the same atomic number, but they have different mass numbers. It can be concluded that isotopes carry the same amount of protons and electrons; it is only the number of neutrons that differ. Therefore, what differs between them is the weight.
Figure 01: Isotopes of Hydrogen
When taking each isotopic form into consideration, the mass of an elemental form can be expressed as an average value, where the individual masses of each isotopic form are averaged out. Also, this is referred to as the ‘atomic mass’ of an element. Therefore, the atomic mass has almost the same numerical value as the mass number, with only a change of a few decimal values. Each number is used for its purposes of convenience depending on the context of use.
What is Gram Molecular Mass?
The gram molecular mass of a molecule is the mass of a mole of that molecule given from the unit “grams”. That means; it is the sum of the masses of molecules present in a mole. It is calculated using the molecular formula of a molecule. Here, the atomic weights of each atom in g/mol unit are added to get the molecular mass.
One mole of a molecule is composed of 6.023 x 1023 molecules. Therefore, the molecular mass is the weight of 6.023 x 1023 molecules. Since the atomic masses of each element are known, it is easy to calculate the molecular mass rather than thinking of a 6.023 x 1023 of molecules.
What is the Difference Between Gram Atomic Mass and Gram Molecular Mass?
Gram atomic mass and gram molecular mass are the same as atomic mass and molecular mass, expressed in the unit “grams”. Therefore, the key difference between gram atomic mass and gram molecular mass is that the gram atomic mass gives the mass of an individual atom, while the gram molecular mass gives the mass of a group of atoms.
The below infographic summarizes the difference between gram atomic mass and gram molecular mass.
Summary – Gram Atomic Mass vs Gram Molecular Mass
Gram atomic mass and gram molecular mass are the same as atomic mass and molecular mass, expressed in the unit “grams”. Therefore, the key difference between gram atomic mass and gram molecular mass is that the gram atomic mass gives the mass of an individual atom, while the gram molecular mass gives the mass of a group of atoms.
Reference:
1. Helmenstine, Anne Marie. “Gram Molecular Mass Definition.” ThoughtCo, Jul. 3, 2019, Available here.
Image Courtesy:
1. “Hydrogen Deuterium Tritium Nuclei Schmatic-en” By Dirk Hünniger;Derivative work in english – Balajijagadesh – This file was derived from: Hydrogen Deuterium Tritium Nuclei Schmatic-de.svg (CC BY-SA 3.0) via Commons Wikimedia