History of Atomic Models

Grade 7 Quarter 1 Science

How many atomic models are there?

5

What was the atomic model that was first made?

Dalton’s Model

Who made the first ever atomic model?

John Dalton

When was the first atomic model made?

1803

Atoms are solid, indivisible spheres. Each element consists of unique atoms with specific weights.

Dalton’s Model

Introduced the concept of atoms as fundamental building blocks of matter. Helped us understand that in chemical reactions, atoms are rearranged.

Dalton’s Model

What is the name of the second atomic model made?

Thomson’s Model ( Plum Pudding Model )

Who made the second atomic model?

Joseph John Thomson

When was the second atomic model made?

1904

Atoms are composed of a positively charged pudding with negatively charged electrons scattered throughout like plums in a pudding.

Thomson’s Model ( Plum Pudding Model )

Introduced the idea that atoms are divisible and contains smaller charged particles. Discovered the electrons, leading to the realization that atoms are not indivisible.

Thomson’s Model ( Plum Pudding Model )

What is the name of the third atomic model?

Rutherford’s Model ( Nuclear Model )

Who made the third atomic model?

Ernest Rutherford

When was the third atomic model made?

1911

Atoms have a small, dense, positively charged nucleus at the center. Electrons orbit the nucleus like planets around the sun.

Rutherford’s Model ( Nuclear Model )

Demonstrated that most of an atoms mass is concentrated in the nucleus. Proposed the nuclear model of the atom, refuting the idea of a uniformly distributed positive charge.

Rutherford’s Model ( Nuclear Model )

What is the name of the fourth atomic model?

Bohr’s Model ( Planetary Model )

Who made the fourth atomic model?

Niels Bohr

When was the fourth atomic model made?

1913

Electrons can orbit the nucleus in specific quantized energy levels or shells. Electrons can jump between levels by absorbing or emitting energy.

Bohr’s Model ( Planetary Model )

Explain the stability of atoms and the emission of light in discrete wavelength. Integrated quantum theory with atomic structure improving our understanding of atomic behavior.

Bohr’s Model ( Planetary Model )

What is the name of the fifth atomic model?

Quantum Mechanical Model

Who made the fifth atomic model?

Erwin Schrodinger & Werner Heisenberg

When was the fifth atomic model made?

1926

Electrons exist in probabilistic orbitals rather than fixed paths. Uses complex mathematical equations to describe electron behavior.

Quantum Mechanical Model

Provides the most accurate and comprehensive description of atomic structure. Explains chemical bonding and properties of elements in terms of electron probability distributions.

Quantum Mechanical Model