The modern atomic theory is based on a model that has evolved over time, thanks to the contributions of many scientists. The earliest model of the atom was proposed by John Dalton in the early 19th century. However, it was not until the turn of the 20th century that a more sophisticated model emerged.

## Dalton’s Model

Dalton believed that atoms were indivisible and indestructible. He also proposed that all atoms of a given element were identical in mass and properties. Moreover, he suggested that compounds were formed by the combination of different elements in fixed ratios.

### Thomson’s Model

In 1897, J.J. Thomson discovered the electron, which led to a radical revision of Dalton’s model. Thomson proposed that atoms were made up of positively charged material with negatively charged electrons scattered throughout like raisins in a pudding. This became known as the “plum pudding” model.

### Rutherford’s Model

Ernest Rutherford conducted an experiment in which he fired alpha particles at thin gold foil and observed their deflection patterns. He concluded that atoms consisted mostly of empty space with a small, dense nucleus at its center. This became known as the “planetary” or “solar system” model.

### Bohr’s Model

Niels Bohr further refined Rutherford’s model by proposing that electrons orbited around the nucleus in specific energy levels or shells. He also suggested that electrons could jump from one energy level to another by absorbing or emitting energy in discrete packets called quanta.

### The Modern Quantum Mechanical Model

The current understanding of atomic structure is based on quantum mechanics, which is a mathematical framework used to describe the behavior of matter and energy at microscopic scales. In this model, electrons are not confined to specific orbits but exist as probability distributions called orbitals.

## Conclusion

In conclusion, the modern atomic theory is based on a model that has undergone significant changes over time. From Dalton’s early concept of the atom as an indivisible and indestructible particle to the current quantum mechanical model, our understanding of atomic structure has evolved thanks to the contributions of many scientists. The use of HTML styling elements such as **, , **

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