Contributions to Atomic Theory Quiz

Questions and Answers

Who was Democritus?

A Greek philosopher

What was Democritus's contribution to atomic theory (What is 'Atomos')?

He proposed that matter, when small enough, reaches a point where it can no longer be divided and becomes atoms, meaning 'indivisible.'

When did Democritus come up with his theory?

Around 440 BC

When and where was John Dalton born?

September 6, 1766, in the UK Signup and view all the answers

What was John Dalton's contribution to atomic theory?

He determined that everything breaks down into specific combinations of elements in the same proportions. Signup and view all the answers

When did John Dalton make his discovery?

Around 1808 Signup and view all the answers

What experiments led John Dalton to his discovery?

He measured masses of different combined elements. Signup and view all the answers

How did John Dalton's new views differ from the views of past scientists?

Rather than every substance having its own element, individual elements created different substances. Signup and view all the answers

How did John Dalton's atomic structure differ from today's?

Atoms were simply particles, not really having any significant features. Signup and view all the answers

When and where was J.J. Thomson born?

December 18, 1856, in England Signup and view all the answers

What was J.J. Thomson's contribution to atomic theory?

He discovered electrons. Signup and view all the answers

When did J.J. Thomson make his discovery?

Around 1906 Signup and view all the answers

What experiments led J.J. Thomson to his discovery?

He measured heat and a magnet's ability to affect cathode rays. Signup and view all the answers

How did J.J. Thomson's views differ from previous scientists'?

Elements now had negatively charged particles. Signup and view all the answers

How did J.J. Thomson's atomic structure differ from today's?

Electrons were thought to be distributed randomly within a positively charged particle. Signup and view all the answers

When and where was Ernest Rutherford born?

August 30, 1871, in New Zealand Signup and view all the answers

What was Ernest Rutherford's contribution to atomic theory?

He discovered a central nucleus of atoms. Signup and view all the answers

When did Ernest Rutherford make his discovery?

1894 Signup and view all the answers

What experiments led Ernest Rutherford to his discovery?

He launched alpha particles through a thin piece of gold foil and observed most particles go straight through, but some deflect. Signup and view all the answers

How did Ernest Rutherford's views differ from previous scientists'?

Atoms now had a nucleus where the positive charge was concentrated and was mostly empty space. Signup and view all the answers

How did Ernest Rutherford's atomic structure differ from today's?

It was closer to today's structure, but lacked electron activity and nuclei. Signup and view all the answers

When and where was Neils Bohr born?

October 7, 1885, in Denmark Signup and view all the answers

What was Neils Bohr's contribution to atomic theory?

He determined the behavior of electrons in an atom. Signup and view all the answers

When did Neils Bohr make his discovery?

Around 1922 Signup and view all the answers

What experiment led Neils Bohr to his discovery?

He repeated the gold foil experiment and paid attention to the way the alpha particles deflected. Signup and view all the answers

How did Neils Bohr's views differ from previous scientists'?

The planetary model was created and portrayed a general idea of the behavior of electrons. Signup and view all the answers

How did Neils Bohr's atomic structure differ from today's?

It was very close and was the same model many look at today (though not the current one), but lacked neutrons. Signup and view all the answers

When and where was James Chadwick born?

October 20, 1891, in England Signup and view all the answers

What was James Chadwick's contribution to atomic theory?

He discovered neutrons. Signup and view all the answers

When did James Chadwick make his discovery?

1932 Signup and view all the answers

What experiments led James Chadwick to his discovery?

He blasted beryllium with alpha particles and observed that a new type of radiation was present. Signup and view all the answers

How did James Chadwick's views differ from previous scientists'?

There was now a particle within atoms containing a neutral charge. Signup and view all the answers

How did James Chadwick's atomic structure differ from today's?

It was very close and contained the same... Signup and view all the answers

Study Notes

Democritus

Greek philosopher proposed the concept of "Atomos," meaning indivisible particles of matter.
His theory emerged around 440 BC, suggesting matter could be broken down until it reached atoms.

John Dalton

Born on September 6, 1766, in the UK.
Made significant contributions to atomic theory around 1808, indicating that matter consists of specific combinations of elements in fixed proportions.
Conducted experiments measuring the masses of different combined elements, contrasting past beliefs where each substance was thought to be its own type of element.
Dalton viewed atoms as simple particles without complex features.

J.J. Thomson

Born on December 18, 1856, in England.
Discovered electrons around 1906, changing the atomic model significantly.
His experiments involved measuring the effects of heat and magnets on cathode rays.
Introduced the notion that elements contain negatively charged particles, leading to a model where electrons were distributed randomly within a positively charged mass.

Ernest Rutherford

Born on August 30, 1871, in New Zealand.
Identified the nucleus of atoms as the central core around 1894.
Conducted the gold foil experiment, where alpha particles passing through showed that atoms are mostly empty space with a concentrated positive charge at the nucleus.
Rutherford's findings shifted the understanding of atomic structure significantly, though his model lacked detail on electron activity.

Niels Bohr

Born on October 7, 1885, in Denmark.
His contributions around 1922 focused on the behavior of electrons within atoms, introducing the planetary model of electrons.
Repeated Rutherford's gold foil experiment, emphasizing the deflection patterns of alpha particles to derive his theories.
Bohr's model was closer to modern concepts, though it did not account for neutrons.

James Chadwick

Born on October 20, 1891, in England.
Discovered neutrons in 1932, adding a crucial element to atomic theory.
His discovery involved blasting beryllium with alpha particles, resulting in a new type of radiation.
The understanding of atomic structure evolved with Chadwick's finding, introducing particles with a neutral charge within atoms, refining the model significantly.

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Description

Test your knowledge on the foundational concepts of atomic theory, focusing on the contributions made by Democritus. This quiz covers key ideas such as the definition of an atom and historical context surrounding Democritus's theories.