What Is Definition of Dalton’s Atomic Theory?


Martha Robinson

Dalton’s Atomic Theory is a fundamental concept in the field of chemistry. It was proposed by John Dalton, an English chemist, in the early 19th century. The theory provides a framework for understanding the behavior of atoms and their interactions with each other.

What is Dalton’s Atomic Theory?

According to Dalton’s Atomic Theory, all matter is made up of tiny particles called atoms. These atoms cannot be created or destroyed in a chemical reaction. Furthermore, all atoms of a given element are identical in their properties such as size, shape, and mass.

Dalton also proposed that chemical reactions occur when atoms combine with each other to form molecules. In these reactions, atoms are rearranged but not destroyed or created. This means that the total mass of the reactants must be equal to the total mass of the products.

The Five Postulates of Dalton’s Atomic Theory

1. All matter is composed of tiny indivisible particles called atoms. 2. Atoms of the same element are identical in properties such as size, shape, and mass. 3.

Compounds are formed when atoms of different elements combine in fixed ratios. 4. Chemical reactions involve the rearrangement of atoms; no new atoms are created or destroyed. 5. The relative numbers and kinds of atoms in a compound can be determined by its chemical formula.

Evidence Supporting Dalton’s Atomic Theory

Over time, many experiments have been conducted that support Dalton’s Atomic Theory. For example, studies on gases showed that they always react in fixed ratios which can be explained by the fact that they consist of different combinations of elements with fixed proportions.

Another example is how elements always react with each other in predictable ways because they have specific numbers and types of atoms that interact with one another.

Limitations and Modifications

While Dalton’s Atomic Theory was groundbreaking at the time it was proposed, it has since been modified and improved based on new scientific findings. For example, it was found that atoms are not indivisible as Dalton originally thought; they can be further broken down into subatomic particles such as protons, neutrons, and electrons.

Additionally, scientists have discovered that atoms of the same element can have different isotopes with varying numbers of neutrons in their nucleus.


In conclusion, Dalton’s Atomic Theory is a cornerstone of modern chemistry. It provides a basic understanding of the behavior of atoms and their interactions with each other. While it has its limitations, it remains a fundamental concept in the field of chemistry and serves as the foundation for further research and discoveries.