The main difference between atom and molecule is that an atom is made up of neutrons, protons and electrons while molecule refers to the group of atoms that are bonded together via covalent bonding or ionic metallic.
Comparison Chart
| Basis of Distinction | Atom | Molecule |
| Definition | Atom refers to the smallest particle of elements that contains the properties of the element | Molecules refer to the group of atoms or combination of atoms |
| Dependency | May or may not | Yes |
| Properties of Matter | May or may not | Yes |
| Classification | No | Two: homo-atomic and hetero-atomic |
| Strength | Basic building blocks of matter | More molecules in human body than stars in the universe |
| Existence | It cannot exist independently | It can exist independently |
| Examples | Oxygen, hydrogen and nitrogen | H2, NO, etc. |
What is Atom?
Atom refers to the smallest particle unit of the simple matter that has the properties of a chemical element. All types of gases, solids, liquids and plasma are composed of ionized or neutral atoms. These are typically very small in size and are unable to be seen through naked eyes and magnifying microscope. The size of an atom can be around ten-billionths of a meter. I talk about their boundaries then these have not well-defined boundaries.
With the gradual development of physics, atomic models have incorporated quantum principles to explain better and predicted behavior of the atom. Every atom composed of one or more electrons bound to the nucleus.
The nucleus of an atom is made of one or more protons and typically has a similar number of neutrons. The nucleus of an atom is also surrounded by the electrons that are negatively charged particles. An atom can be negatively or positively charged depending on the majority of the particles. When these negatively or positively atoms bond together to form molecules, the bonds are formed by the electrons filling up the outer orbits of the atoms. There is no bonding in an atom as atoms exist independently.
What is Molecule?
A molecule is the smallest particle of an electrically neutral group that contains the chemical properties of that compound or element. These are made up of the atoms that are held together by chemical bonds. These are entirely distinguished from ions because of lacking electrical charge.
The atoms of most of the chemicals quickly bond with other atoms to form molecules. These can vary in size and complexity. These always remain in motion. In liquids and solids, they are packed tightly together. In the solid-state, their motion can be likened to rapid vibration. In the liquid state, these move freely among each other in a sort of slithering fashion. In gas state, their density is less as compared to solid and liquid of the same chemical bond and move even more freely as compared to liquid.
As compared to an atom, the molecule has the capability to exist by itself that is because of the electron present in the atom. In the molecule, the atom can be stable only in case of the availability of a sufficient number of electrons. According to the Kinetic Theory of Gasses, “molecule is often used for any gaseous particle regardless of its composition. Due to the monoatomic molecular structure, Noble gas atoms are also considered as molecules.”
Key Differences between Atom and Molecule
- An atom is the smallest particle of an element while the molecule is the smallest particle of the compound.
- Atom may or may not exist independently while the molecule always exists independently.
- Atom may or may not have properties of a matter while the molecule always possesses properties of matter.
- Molecules are composed of atoms atom is made up of neutrons, protons, and electrons.
- An atom may be a molecule due to independent existence. Atoms are present in a monoatomic molecule due to stability factors like noble gasses and helium whereas molecule cannot say that atom.
- Atoms have no further kinds while molecules have two types that are homo-atomic molecules and heteroatomic
- Atoms have no bonding at all while molecules have inter-molecular forces and intramolecular
- The arrangement of atoms can be seen with x-rays while in molecules, interaction allows the human being to move, sense, reproduce and lots of other things.
- Three different types of an atom are a hydrogen atom, deuterium atom, and a tritium Two types of molecule are simple molecule and complex molecule.
- Atom cannot exist independently while a molecule can exist independently.
- An atom of an element cannot live in the free state while molecules can live in the free state.
- Mass of an atom can’t be determined practically while the sum of masses of the individual atoms constitutes the mass of a molecule.
- Atoms can gain and lose electrons to form ions while molecules can’t gain or lose electrons to form ions.
- It is impossible to see an atom through the naked eye and even through a magnifying The molecule also cannot be seen through naked eye but can be seen through a highly magnifying microscope.
- Atom cannot be further divided while molecule can further be divided to give individual atoms.
- Atom has a nuclear attraction or bonding with it while the molecule has a chemical attraction or bonding between the atoms.