Atomic Theory Timeline

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Questions and Answers

Which scientist proposed that matter is made of atomos, meaning 'indivisible'?

Democritus (correct)

J.J. Thomson

John Dalton

James Chadwick

John Dalton discovered the neutron.

False

What significant experiment did Ernest Rutherford conduct to explore atomic structure?

Gold Foil Experiment

J.J. Thomson is associated with the __________ Model.

Blueberry Muffin Signup and view all the answers

Which of these scientists contributed to the discovery of radioactivity?

Marie Curie Signup and view all the answers

The planetary model of the atom was proposed by James Chadwick.

False Signup and view all the answers

What particle did James Chadwick discover?

Neutron Signup and view all the answers

Match the scientists with their respective contributions:

Democritus = Matter is made of atomos John Dalton = Developed the Atomic Theory J.J. Thomson = Discovered the electron Marie Curie = Discovered radioactivity Signup and view all the answers

What did Max Planck propose about energy emission?

Energy is emitted in discrete quantities. Signup and view all the answers

The photoelectric effect could be explained using the current model of light before Einstein.

False Signup and view all the answers

What are photons?

Packets of energy or quantized particles of light. Signup and view all the answers

Electrons can only exist in specific orbits with specific amounts of energy associated with them. These orbits are referred to as __________.

allowed orbits Signup and view all the answers

What happens when neon gas is excited?

It produces colored light with a non-continuous spectrum. Signup and view all the answers

Match the following scientists with their contributions:

Max Planck = Proposed quantized energy Albert Einstein = Introduced the concept of photons Niels Bohr = Developed the Bohr model of the atom Photoelectric Effect = Explains light's interaction with matter Signup and view all the answers

Electrons can absorb only a part of a photon in their interactions with matter.

False Signup and view all the answers

When white light is dispersed through a prism, it produces a __________ spectrum.

continuous Signup and view all the answers

Study Notes

Atomic Theory Timeline

Democritus ( ~400 BC): Proposed matter is made of indivisible particles called "atomos".
John Dalton (1803): Developed the atomic theory stating that elements consist of atoms that cannot be divided, created, or destroyed.
J.J. Thomson (1897): Discovered the electron using the cathode ray tube experiment. He found negatively charged particles within atoms.
Marie Curie and Henri Becquerel (1896): Discovered radioactivity, finding that some elements emit positively charged alpha particles, negatively charged beta particles, and electromagnetic radiation (gamma rays).
Ernest Rutherford (1911): Conducted the gold foil experiment. This experiment suggested the atom is mostly empty space, with a dense, positively charged nucleus.
James Chadwick (1932): Discovered the neutron, a neutrally charged particle found in the nucleus.
Max Planck (1900): Proposed that energy is emitted in discrete packets (quanta), not continuously. This was a key concept in the development of quantum mechanics.

Atomic Models

Billiard Ball Model (Dalton): Depicted atoms as solid, indivisible spheres.
Blueberry Muffin Model (Thomson): Visualised atoms as a positively charged "dough" with negatively charged electrons scattered throughout.
Planetary/Nuclear Model (Rutherford): Showed an atom with a tiny, positively charged nucleus at the center and electrons orbiting it like planets around the sun.
Bohr Model (Bohr): Electrons orbit the nucleus in specific energy levels, and can jump between energy levels by absorbing or emitting photons of light.

Key Concepts

Radioactivity: The property of some elements to spontaneously emit particles and radiation.
Nucleus: The dense, positively charged center of an atom.
Electron: A negatively charged particle found orbiting the nucleus.
Neutron: A neutrally charged particle found in the nucleus.
Quantized Energy: Energy that exists only in discrete amounts (not continuous).
Photon: A packet of light energy.

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Description

Test your knowledge on the key developments in atomic theory from ancient philosophers to modern scientists. This quiz covers significant figures and their contributions, including Democritus, Dalton, Thomson, and Curie. Explore the evolution of atomic understanding over centuries!