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Molecular Compounds with Examples for NEET

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Last updated date: 17th Apr 2024
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Introduction to Molecule

A molecule is the simplest unit with the fundamental chemical properties of a covalent compound, just as an atom is the simplest unit with the fundamental chemical qualities of an element. The term molecular compound is used to denote elements that are covalently bound. Covalent molecules occur for several pure elements. Natural diatomic molecules of hydrogen, nitrogen, oxygen, and halogens are H2, N2, O2, F2, Cl2, Br2, and I2. Similarly, a few pure elements, such as elemental phosphorus and sulfur, exist as polyatomic molecules, such as P4 and S8.


Definitions of Molecular and Ionic Compounds with Examples and their Differences

Molecular Compounds

Molecules having the same formula as the number of atoms bound together in the molecule make up a molecular compound. The atoms are bonded together to form a particular shape that is specified by the angles between the bonds and the length of the bonds. Because they share electrons via covalent bonds, these are also known as covalent compounds. Water, ammonia, and carbon dioxide are some examples.


Octet Rule

According to the octet rule, atoms are most stable when their valence shells are filled with eight electrons. It is based on the fact that the atoms of the main group elements have a tendency for chemical bonding, resulting in each atom in the final molecule having eight electrons in the valence shell. Only the core group elements are subject to the octet rule.


The octet rule is known to apply to halogens, oxygen, nitrogen, and carbon molecules. The s-block elements and the p-block elements are examples of elements that follow this rule in general (except hydrogen, helium, and lithium).


Ionic Compounds

Compounds containing charged metal and nonmetal species are known as ionic compounds. Ions are charge-carrying particles that can be either positively or negatively charged. An anion is a negatively charged ion, while a cation is a positively charged ion. Ionic compounds are generated when electrons are transferred between different atoms to form ionic bonds. Sodium chloride and calcium oxide are two examples of ionic compounds.


Difference between Ionic Compound and Molecular Compound

Sr.No

Ionic Compounds

Molecular Compounds


Ionic compounds are made up of ionic bonds in which the atoms are attracted to each other electrostatically.

Covalent bonds are formed when electrons are shared amongst the atoms involved in the synthesis of a molecular molecule.


The interaction of cations and anions produces ionic compounds.

The interaction of neutral atoms produces molecular compounds.


In the liquid media, ionic chemicals operate as a good conducting medium.

Electrical conductivity is poor in molecular molecules.


Because ionic connections are the most powerful sort of chemical link, most compounds are solids with extremely high melting temperatures.

Covalent bonds are quite weak in nature hence, most compounds exist in the gaseous phase.


Properties of Molecular/Covalent Compounds

The following are molecular compound properties:

  • The melting points of covalent compounds are usually low. These compounds have low boiling points, with the exception of molecules of silica and diamonds, which have a high melting point. 

  • This is due to the weak force of attraction that exists between the many linked atoms. These atoms are held together by Van der Waals forces.

  • Gases and liquids with low boiling and melting points are the most common types of these substances.

  • Graphite-like soft textures characterize solid covalent compounds. Because a cloud of electrons exists between each layer of carbon atoms, this is the case.

  • These chemicals are electrical charge non-conductors. The lack of charged ions is the primary cause of this. Graphite is an exception, as it contains a cloud of electrons. Graphite is a good conductor as a result of these properties.

  • They are also poor heat conductors. Their molecules are devoid of free electrons, obstructing the transmission of heat energy.

  • Polar properties are not a typical property of covalent molecules. As a result, these compounds are water-insoluble. Water molecules are not completely neutral; they have a slight negative charge on the oxygen atom and a slight positive charge on the hydrogen atoms. Because covalent compounds are made up of neutral or minorly charged molecules, they are not strongly attracted to water molecules.

 

List of Molecular Compounds

Molecular Formula of Compounds

The molecular formula of a chemical molecule gives us a clear picture of how many elements are contained in that compound. The elements are represented in molecular formulae by their corresponding symbols from the periodic table, and the number of atoms in each element in the molecule is indicated in subscript. The chemical formula for glucose, for example, is C6H12O6.


some molecular compounds examples with their formulas and respective molecular mass


The table below enlists the molecular formula and molecular mass of compounds that are covalent in nature.

Sr. No

Compound Name

Molecular Formula

Molecular Mass


Hydrochloric acid

HCl

36.458 $\dfrac{g}{mol}$


Sulphuric acid

H2SO4

98.072 $\dfrac{g}{mol}$


Ammonia

NH3

17.031 $\dfrac{g}{mol}$


Carbonic acid

H2CO3

62.024 $\dfrac{g}{mol}$


Nitric acid

HNO3

63.012 $\dfrac{g}{mol}$


Phosphoric acid

H3PO4

97.994 $\dfrac{g}{mol}$


Ethanol

C2H5OH

46.069 $\dfrac{g}{mol}$


Nitrous acid

HNO2

47.013 $\dfrac{g}{mol}$


Methane

CH4

16.043 $\dfrac{g}{mol}$


Chlorine gas

Cl2

70.90 $\dfrac{g}{mol}$


Butane

C4H10

58.12 $\dfrac{g}{mol}$


Formaldehyde

CH2O

30.031 $\dfrac{g}{mol}$


Formic acid

HCOOH

46.03 $\dfrac{g}{mol}$


Ethane

C2H6

30.07 $\dfrac{g}{mol}$


These are some of examples of the molecular compounds 


Summary

The above article elucidates the information regarding molecular compounds which are also referred to as covalent bonds. These compounds are formed by the sharing of electrons and possess many salient properties. They are different from ionic bonds in several ways in structure and conductance. The article also enlists different types of molecular compounds along with their respective molecular formula and masses.

Competitive Exams after 12th Science

FAQs on Molecular Compounds with Examples for NEET

1. Which types of bonds are found in molecular compounds and how do we identify them?

To distinguish molecular compounds from ionic compounds, the term "molecular compound" is used to denote elements that are covalently bound. Covalent molecules occur for several pure elements.


Molecular compounds form covalent bonds which can be predicted by knowing the location of the elements bonded to each other in the periodic table. Compounds having metals and non-metals bonded to each other are considered ionic compounds, while the compounds in which non-metals are bonded to each other are considered covalent or molecular compounds.

2. Which bonds are stronger covalent or ionic and what is Fajan’s rule?

Ionic bonds are much stronger as compared to the covalent bonds as there is transfer of electrons that occurs resulting in the formation of positive and negative ions and the electrostatic force attraction between ions is very strong. 


Fajan's rule is based on polarization, which claims that as an anion's polarisation rises, its covalent nature increases. The polarising power of the cation and the polarizability of the anion are the two essential elements that influence the extent of polarization of an anion.