Atomic Mass and Molecular Mass

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Atomic Mass of Iron

Each particle of matter has some measure of mass related with it whether little or huge. Everything is composed of atoms. Mass of an atomic particle is known as the atomic mass. This is usually expressed according to the international arrangement as far as a brought together atomic mass unit (amu). 

It very well may be best characterized as 1/12th of the mass of a carbon-12 atom in its ground state. The mass of an atom can be represented by the whole of the mass of protons and neutrons which is practically equal to the atomic mass. This little change is because of the coupling energy mass misfortune. 

1 amu = 1.66  x 10-24 g

The atomic weight of an atom is a dimensionless number when it is isolated by bound together atomic weight or Daltons. 

This is known as the total isotopic mass. 

The atomic masses of elements change from 1.008 amu for hydrogen up to 250 amu for elements which have an extremely high atomic number. 

Mass of molecules can be dictated by including the normal atomic mass of every atom in the molecule. 

In this article, we will learn about atomic mass and molecular mass, what is the atomic mass of iron, what is the atomic mass of potassium, and learn in general about the atomic and molecular masses.

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Atomic Mass of Different Elements

Given below are atomic masses of different elements.

Atomic Mass of Iron

55.845 u

Atomic Mass of Chlorine

35.453 u

Atomic Mass of Sulphur

32.065 u

Atomic Mass of Copper

63.546 u

Atomic Mass of Potassium

39.0983 u

Atomic Mass of Nitrogen

14.0067 u

Atomic Mass of Calcium

40.078 u

Atomic Mass of Phosphorus

30.973762 u

Atomic Mass of Sodium

22.989769 u

What is Molecular Mass? 

Let us now look at what is molecular mass.

The molecular mass of a compound refers to the total of all the atomic masses of the atoms which form a compound. 

Molecular mass is the measure of mass related to a molecule. It is likewise called atomic weight. It tends to be determined by including the mass of every atom duplicated by the number of atoms of the element present in the molecule. For example, water consists of 2 hydrogen atoms and 1 oxygen atom. Mass of the water molecule is equal to the normal atomic mass of hydrogen increased by two or more the atomic mass of oxygen. The molecular mass of elements relies on the constituent atoms of the molecule. 

The molecular mass of molecules can be controlled in the following way: 

  1. Mass Spectrometry: This technique is commonly utilized in deciding the mass of little molecules. This is accounted for as monoisotopic mass. 

  2. Hydrodynamic Strategy: The weight is resolved according to Mark-Houwink relations. This technique requires calibration subsequently it is likewise depicted as a relative atomic weight determination strategy. 

  3. Static Light Scattering: Molecular weight is resolved from the measure of light dispersed utilizing the Zimm technique. 

Key Takeaway Points

  1. All matter is composed of atoms. 

  2. Elements are substances composed of just one sort of atom. 

  3. Atoms have a focal nucleus which contains protons and neutrons. 

  4. Electrons tend to move in orbits around the nucleus. 

  5. Protons’ relative mass is 1 and they have a positive charge. 

  6. Neutrons’ relative mass is 1 and they are neutral.

  7. Electrons have a very negligible mass and a negative charge. 

Solved Example

Question: What is the molar mass of sulfur trioxide SO3, an atomic compound? 

Solution: By definition, the molar mass of SO3 equals its atomic mass in grams. Hence, the calculation of the molar mass of SO3 is needed first. 

The molecular mass (also called as formula mass) of a compound refers to the total of the atomic masses of the apparent multitude of atoms in the molecule. The molecular mass of  SO3 with 4 atoms in its molecule, is given by,

1S = 1 x 32.07 amu 

= 32.07amu 

3O = 3 x 16.00 amu

= 48.00amu 

Therefore, the molecular mass of  SO3 is 80.07 amu.

FAQ (Frequently Asked Questions)

1. What are the Atomic and Molecular Masses of iron and potassium?

Ans: The iron and potassium molecular mass and atomic mass are as follows:

Iron is a metallic element denoted by the symbol Fe. It is an important constituent in haemoglobin, iron-binding proteins, and cytochromes. It also plays a vital role in cellular redox reactions and oxygen transport. 

The atomic mass of iron is 55.85 or approximately 56 and the molecular mass of iron is 55.845 grams/mol. 

The atomic and molecular mass of potassium is as follows:

The atomic mass of k is 39 and the molecular mass of k is 39.0983 g/mol.

2. What are the Atomic Mass and Atomic Mass Number?

Ans: Atomic mass (denoted by the symbol ma) refers to the mass of the single atom of a given chemical element. It consists of three atomic particles that are electrons, protons, and neutrons. In Chemistry, the atomic mass plays a vital role since it is the connection which you can measure in the Chemistry laboratory between moles and mass, that is the number of atoms. Most of the things that we study in chemistry depend on the proportions of the atoms.

The atomic mass number refers to the total number of nucleons, which are the total number of both protons and neutrons together, in the atomic nucleus. It is denoted by the symbol A and is also called as the nucleon number.