What is a Molecule? (Definition, Example & Explanation)

Hi everyone, today I’m here with a new topic which is about a molecule, what is a molecule in Chemistry, its definition, example, and explanation. Further, we describe briefly molecular and empirical formula, molecular geometry, and molecular spectroscopy. If you have any questions about this topic then let me know in the comment section.

What is a Molecule?

When two or more than two atoms combine chemically then a molecule is formed. A molecule is a combination of two same or different atoms. They are an electrically neutral group of two or more two atoms that are held very close together with the help of chemical bonds.

Example: When two hydrogen atoms and one oxygen atom combines chemically then it forms one molecule of water.

2H2+ O2 → 2H2O

Similarly, when calcium (Ca) atom chemically combines with Oxygen(O) atom it forms one calcium oxide molecule.

Ca2+ + O2- → CaO


To understand about molecule let’s understand about an atom first. Atoms are the smallest particles of a matter or compound. They are single neutral compounds. Atoms are the smallest particles of a matter or compound. They are single neutral compounds.

If a lone hydrogen atom happens to pass close enough to another lone hydrogen atom their electrons, which are attracted like magnets to protons can pull the atoms towards each other until they collide and stick together (this reaction usually requires assistance from an additional substrate).

An argon atom will not usually bond with anything. Even though possible bond numbers per atom are pretty small, huge molecules can form if bonds happen to be properly arranged.

For example, even though hydrogen can only form one bond a standard water molecule is always made of three atoms of a Water Molecule (2 Hydrogen and 1 Oxygen atom). This is possible because oxygen which can form two bonds forms just one bond with a hydrogen atom.

A single molecule of the sugar known as Glucose is made of 24 atoms, a special arrangement of carbons, hydrogens, and oxygens (12 Hydrogens, 6 Carbons, and 6 Oxygens).

Now let’s talk about bonding between molecules.


Molecules are being held together by either ionic bonding or covalent bonding. Various types of non-metal elements exist only as molecules in the environment. For instance, hydrogen only exists as a hydrogen molecule. Molecules of a compound are made out of two or more elements. As we know a molecule that is made out of two or more atoms of a single element is known as a homonuclear molecule.what is a molecule

Chemical Formula of Molecules

Molecule uses the chemical formula for one line of chemical element symbols, numbers, and sometimes also other symbols, such as parentheses (), dashes (___), brackets, plus (+), and minus (−) signs. These are limited to one typographic line of symbols, which may include subscripts (x2) and superscripts (x2).what is a molecule

The simplest type of chemical formula is an empirical formula which is the integral ratio of the chemical elements that constitute it. For example, water is always composed of a ratio of 2:1 hydrogen to oxygen atoms respectively, and ethanol (ethyl alcohol) is always composed of ratio 2:6:1 of carbon, hydrogen, and oxygen respectively.

The type of chemical formula that reflects the exact number of atoms that compose the molecule and so characterizes different molecules is known as the molecular formula. Although different isomers may have the same atomic constitution while being different molecules. The molecular formula is often the same as the empirical formula but not always.what is a molecule

For example, the molecule acetylene has the simplest integer ratio of elements (empirical formula) is CH but the molecular formula is C2H2.

Molecular Geometry

Molecules have fixed angles, bond lengths, and equilibrium geometries about which they continuously sway through rotational and vibrational motions. A pure compound is constituted of molecules with the same average geometrical structure. The structure of a molecule and chemical formula are the two important factors that determine its properties, particularly its reactivity. Isomers share a chemical formula but generally have very different properties because of their different structures.what is a molecule

Molecular Spectroscopy

Molecular spectroscopy deals with the retaliation (spectrum) of molecules interrelating with exploring signals of known frequency or energy (according to Planck’s formula). Molecules have measured energy levels that can be probe by detecting the molecule’s energy exchange through absorbance or emission.Spectroscopy does not generally refer to the diffraction studies where particles such as electrons, neutrons, or high energy X-rays interact with a regular arrangement of molecules (as in a crystal). what is a molecule

Microwave spectroscopy is used to identify molecules in outer space and generally observe changes in the rotation of molecules. Infrared spectroscopy observes the vibration of molecules, including bending, twisting, and stretching motions.

 It is normally used to identify the kinds of functional groups or bonds in molecules. Changes in the grouping of electrons flex emission or absorption lines in visible or near-infrared light ultraviolet and result in color. Nuclear resonance spectroscopy measures the environment of particular nuclei in the molecule and can be used to identify the numbers of atoms in different positions in a molecule. what is a molecule

What is a Molecule in Simple Terms?

A molecule can be loosely thought of as a group of atoms stuck together usually through a chemical bond. It is made of one positively charged proton in its nucleus and one negatively charged electron.

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