Difference Between Molecule and Compound for JEE Main 2024

A molecule is a unit or particle that consists of two or more atoms that are chemically held together; the number of atomic nuclei making up a molecule is a determinate number. For instance, HCl is a molecule consisting of one hydrogen atom bonded to one chlorine atom. It is made of two atoms and is known as a diatomic molecule.

A crystal or rock of NaCl is not a molecule: it is an ionic lattice consisting of an uncertain number of atoms or units. Carbon dioxide CO₂ is a molecule consisting of two oxygen atoms bonded to a carbon atom. It contains three atoms, so it is called a triatomic molecule. Silicon dioxide - well-known as quartz - occurs as a large covalent network made up of an uncertain number of atoms.

One of the most copious triatomic molecules in the world is the H3+ trihydrogen cation. Although abundant in space, where it has become stable by the very low temperature and the low density of matter, on earth the trihydrogen cation is rare. Very big molecules occur; they are identified as macromolecules. An instance of a particularly big macromolecule is DNA, which holds hundreds of billions of atoms.

Homonuclear vs Heteronuclear

The only method to classify molecules is whether they are homonuclear, they consist of only one element, like H₂, O₂, O₃, P₄, N₂, and S₈; heteronuclear, consist of more than one element, like NO₂, CH₄, PCl₅, CO, and C₆H₁₂O₆.

Images of two molecules: On the left side is S8, which is homonuclear.  On the right side is PCl₅, which is heteronuclear. Solid, Liquid, or Gas: Polar vs Non-Polar MoleculesWhether a material made of molecules is any of the matter such as solid, liquid, or gas at standard room temperature is measured by the molecules' molar mass and the strength of electrostatic attraction among molecules. Low molar mass molecules, such as CH₄ and H₂, are likely to form gases. Strong electrostatic attraction among molecules can have a major effect.

For instance, water (H₂O) molecules have the same molar mass as CH₄ molecules. Water begins to boil at 100 °C and methane begins to boil at -161.5 °C. The big difference in boiling points rises from the electronegativities of oxygen and hydrogen creating a dipole in the water molecule. The water molecule is polar; its hydrogen atoms have a long-lasting partial positive charge; the oxygen atom has a long-lasting partial negative charge. The result of these eternal charges is strong, relatively permeate polar bonding between individual water molecules, leading to an unpredictably high boiling point for a material whose molar mass is low. The only bonding between them is van der Waals, methane molecules, forming much weaker links between molecules than polar bonding. A Van der Waals bond occurs when relative nucleus vs electron positions in different molecules briefly produce a fleeting electrostatic attraction among them.

Weak temporary van der Waals forces transport molecules of methane together.  Solid, relatively permanent polar bonding between somewhat negative oxygen and somewhat positive hydrogen carries water molecules together. 

Compound Definition

A compound is a chemical type that is developing when two or more atoms combine chemically, with the help of covalent or ionic bonds.

Compounds may be classified according to the kind of chemical bonds holding the atoms together:

• Molecules are bonded together by covalent bonds.

• Ionic compounds are bonded together by ionic bonds.

• Intermetallic compounds are bonded together by metallic bonds.

• Complexes are frequently held together by coordinate covalent bonds.

Chemical Formula:

Compounds are characterized by their chemical formula. A chemical formula is a piece of information or detail about the parts of atoms that create a specific chemical compound.

The chemical formula of water is H₂O which displays two atoms of hydrogen and one atom of oxygen combined to produce one molecule of H₂O. The chemical formula for common salt or table salt is NaCl which shows one atom of sodium and one atom of chlorine combined to produce one molecule of NaCl. 

Types of Compounds

Compounds can be categorized into two types, molecular compounds, and Salts. In molecular compounds, atoms combine with each other via covalent bonds. In salts, it is bound together with ionic bonds. These are the two kinds of bonds out of which each compound is made.

Example of Compounds:

• Compounds comprise Hydrogen Peroxide (H₂O₂) and water (H₂O) etc. You can see water’s chemical formula, it states it has 2 atoms of Hydrogen joined with 1 atom of oxygen and in hydrogen peroxide, it has 2 atoms of hydrogen and two those atoms of oxygen.

• Compounds contain table salt or common salt sodium chloride (NaCl, an ionic compound), sucrose (a molecular compound), nitrogen gas (N₂, a covalent compound), a sample of copper (intermetallic compound), and water. (H₂O, a covalent molecule). Samples of chemical species not taken into consideration compounds contain the hydrogen ion H+ and the noble gas elements (e.g., argon, neon, helium), which do not readily form produce bonds.

Examples of Some Commonly used Compounds along with Molecular Formula:

Compound versus Molecule

Occasionally a compound is called a molecule. Generally, the two words are synonymous. Some scientists make merit between the kinds of bonds in molecules (covalent) and compounds (ionic). 

Difference Between Molecule and Compound

These were the key differences between molecules and compounds.

Overview of Compound and Molecule provided by Vedantu

Science is all about the systematic study of the various terms that are taught in schools. There are thousands of terms that students have to memorise and compounds and molecules are the most basic foundation of chemistry. Therefore it is important to know their meaning and the difference between them. Vedantu has made this task easier for students as we have made study material that clears the basic foundation of the molecule and a compound. The study notes provided by Vedantu make complex concepts easy to understand and therefore students can get a clear understanding of the difference between a molecule and a compound after reading this article and the study notes that are provided in a PDF format.

The concept of compound and molecule can get a little confusing as compounds and molecules are very closely related. All compounds are molecules however the difference is that all molecules are not compounds. To get a clear view of compounds and molecules, Vedantu’s website has given a detailed breakdown of molecule versus compound. The article on Vedantu contains information on the definition of molecule and compound, its formulas, types, and various examples are also given so that students can get a better understanding of both concepts.

Molecules and Compounds are taught in various chapters of the NCERT books like Atoms and molecules, chemical bonding and molecular structure, coordination compounds etc. These are the main NCERT chapters in which the concept of molecules and compounds is briefly discussed.

To understand the concept of molecules in detail it is important to first get a clear view of what atoms are. Atoms are structures that contain electrons, neutrons and protons, both electrons and protons have a negative and positive charge. Atoms need to be chemically balanced and therefore they will bond with other atoms to get a balanced equation. When the bonding of atoms takes place either in the same type or different type it forms a molecule for example H2O is a molecule. Molecules are invisible to the naked eye and therefore scientists’ break them down into their atomic parts. For example, water contains two hydrogen atoms and one oxygen atom and therefore the chemical formula of water is H2O which is a molecule.

Some examples of molecules are – oxygen O2, ozone 03, nitrogen N2, carbon dioxide CO2, sulphuric acid H2SO4. All of these elements have at least two atoms in them and therefore they are called molecules.

We discussed earlier that all compounds are molecules. Compounds come into existence when two atoms containing different elements combine. For example, carbon dioxide or CO2 is a compound because it has two different elements that are bonded. Similarly, water H2O is a compound but oxygen O2 is a molecule and nitrogen N2 is also a molecule. Some examples of compounds are – baking soda in HCO3, salt NaCl, ammonia NH3, vinegar C2H402. This is the main difference between a compound and a molecule.