TED-ED: The 2,400-year search for the atom - Theresa Doud

The video explores the evolution of atomic theory, starting with Democritus's idea of indivisible particles called atomos. It covers John Dalton's revival of atomic theory in the 19th century, J.J. Thomson's discovery of the electron, and Ernest Rutherford's nuclear model. Niels Bohr's contributions and the development of quantum theory are also discussed, highlighting the complexity and ongoing evolution of our understanding of atoms.

Who first proposed the idea that everything is made up of tiny particles called atomos?

• Aristotle

• J.J. Thomson

• Democritus

• John Dalton

What did John Dalton demonstrate about common substances?

• They contain electrons.

• They are composed of indivisible particles.

• They break down into the same elements in the same proportions.

• They are made of four elements.

Which model of the atom did J.J. Thomson propose?

• Chocolate chip cookie model

• Quantum model

• Nuclear model

• Planetary model

What was the key finding from Rutherford's gold foil experiment?

• Atoms are solid spheres.

• Atoms have a dense nucleus.

• Atoms are indivisible.

• Electrons orbit the nucleus.

What did Niels Bohr propose about electron orbits?

• Electrons are confined to a single point.

• Electrons are stationary.

• Electrons orbit randomly.

• Electrons orbit at fixed energies and distances.

Which principle did Werner Heisenberg introduce?

• Conservation of mass

• Uncertainty principle

• Theory of relativity

• Law of definite proportions

What happens when electrons shift between energy levels in an atom?

• They release or absorb energy as light.

• They disappear.

• They change into protons.

• They become stationary.