In your surrounding, you might have observed there are millions of objects, which are created out of matter and the matter comprises of molecules, which is a combination of two or more atoms bonded together. So, in short, atoms are grouped together to form a molecule, which embodies the objects around us. The whole universe is made up of the atom, and they are so small particles of an element, that we are not able to see them through bare eyes or even via microscope, but they do exist in each and every object and are affected by our activities.
What is the difference between atoms and molecules, is the basic question that arises in the mind of every chemistry student. They often face difficulty in understanding them correctly, as both of these two are a tiny identifiable unit.
Content: Atom Vs Molecule
|Basis for Comparison||Atom||Molecule|
|Meaning||The tiny particle of a chemical element, which may or may not exist independently is called an atom.||Molecules refers to the set of atoms held together by bond, indicating the smallest unit of a compound.|
|Existence||May or may not exist in free state.||Exist in free state.|
|Comprise of||Nucleus and electrons.||Two or more, identical or different atoms, bonded chemically.|
|Shape||Spherical||Linear, angular and triangular|
|Visibility||Neither visible through naked eyes, nor magnifying microscope.||Not visible through naked eyes, but can be seen with the help of magnifying microscope.|
|Reactivity||Highly reactive, subject to certain exceptions||Comparatively less reactive.|
|Bond||Nuclear bond||Covalent bond|
Definition of Atom
The term ‘atom’ in chemistry represents the elementary unit of ordinary matter that exist in free state and contains all chemical properties. It is an infinitesimal particle that distinctively identifies a chemical element. It is composed of a positively charged nucleus and surrounded by negatively charged electrons.
The nucleus consists of protons and neutrons which group together at the middle of an atom. These protons and neutrons have almost equal masses, but they vary in charge i.e. the former carry positive charge while the latter do not carry the electric charge. The positive charge in an atom is equivalent to the negative charge. Thus it is electrically neutral. In addition to this, the protons and neutrons are made up of constituents, i.e. quarks and gluons.
Example: H, He, Li, O, N
Definition of Molecule
The molecule is a small unit of matter, which exist in free state and represents the chemical properties of the substance.
When two or more atoms are extremely close to each other, such that the electrons of the atoms can interact with one another, resulting in attraction between the atoms, called as a chemical bond. The chemical bond takes place as a result of the exchange of electrons between atoms, specifically known as a covalent bond. So, when two or more atoms are clustered together as a single unit, with the help of covalent bond, it forms a molecule.
If one or more identical atoms exist as a unit, independently, it is known as a molecule of an element, but if two or more varying elements are grouped together in a fixed proportion, by mass, to create a unit that exists freely, is termed as a molecule of a compound.
Key Differences Between Atom and Molecule
The difference between atom and molecule can be drawn clearly on the following grounds:
- Atom is defined as the smallest unit of an element which may or may not exists independently. On the other hand, molecule implies the set of atoms held together by the bond, indicating the smallest unit of a compound.
- Atoms may or may not exist in the free state, but molecules exist in the free state.
- Atoms comprise of the nucleus (which contains protons and neutrons) and electrons. Conversely, a molecule comprises of two or more, identical or different atoms, combined chemically.
- The shape of an atom is spherical whereas the molecules can be linear, angular or rectangular in shape.
- Atoms are highly reactive, i.e. they participate in the chemical reaction without additional decomposition into subatomic units. However, this is not applicable to noble gas atoms. On the contrary, molecules are less reactive, as they do not take part in the chemical reaction.
- Atoms possess nuclear bond, as it entails electrostatic attraction between the nucleus and electron. In contrast, there exist a chemical bond between atoms of a molecule, such that it encompasses single, double or triple bonds.
By and large, there are some dissimilarities amidst the two topics. Both are tiny units, but as molecules are made up of atoms, the size of an atom is much smaller than a molecule. Moreover, to form ions, atoms gain or lose electrons, which is not in the case of a molecule.