Question

atomic theory and basic structure
contributor/date\tcontribution\tmodel (sketch)
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Explanation:

This table is about Atomic Theory and Basic Structure, which falls under Chemistry (a subfield of Natural Science). To fill it, we can list key contributors:

1. John Dalton (1803):

• Contribution: Proposed the atomic theory (atoms are indivisible, elements have unique atoms, compounds have fixed atom ratios).
• Model: Solid sphere model (atoms as hard, indivisible spheres).

1. J.J. Thomson (1897):

• Contribution: Discovered electrons, proposed plum - pudding model (atoms have positive charge with electrons embedded like plums in pudding).
• Model: Sphere of positive charge with embedded electrons.

1. Ernest Rutherford (1911):

• Contribution: Gold foil experiment showed atoms have a small, dense, positive nucleus; electrons orbit around.
• Model: Nuclear model (nucleus at center, electrons orbit).

1. Niels Bohr (1913):

• Contribution: Electrons orbit nucleus in fixed energy levels (shells); explained spectral lines of hydrogen.
• Model: Planetary model (electrons in circular orbits around nucleus).

1. Erwin Schrödinger (1926):

• Contribution: Developed quantum mechanical model (electrons exist in orbitals - probability clouds around nucleus).
• Model: Electron cloud model (regions of high electron probability).

Answer:

Contributor/date	Contribution	Model (sketch)
J.J. Thomson (1897)	Discovered electrons, proposed plum - pudding model	Sphere of positive charge with embedded electrons
Ernest Rutherford (1911)	Gold foil experiment showed small, dense, positive nucleus; electrons orbit	Nuclear model (nucleus at center, electrons orbit)
Niels Bohr (1913)	Electrons in fixed energy levels (shells); explained hydrogen spectral lines	Planetary model (electrons in circular orbits)
Erwin Schrödinger (1926)	Developed quantum mechanical model (electrons in orbitals - probability clouds)	Electron cloud model (regions of high electron probability)