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?
Signup and view all the answers
What was John Dalton's contribution to atomic theory?
Signup and view all the answers
When did John Dalton make his discovery?
Signup and view all the answers
What experiments led John Dalton to his discovery?
Signup and view all the answers
How did John Dalton's new views differ from the views of past scientists?
Signup and view all the answers
How did John Dalton's atomic structure differ from today's?
Signup and view all the answers
When and where was J.J. Thomson born?
Signup and view all the answers
What was J.J. Thomson's contribution to atomic theory?
Signup and view all the answers
When did J.J. Thomson make his discovery?
Signup and view all the answers
What experiments led J.J. Thomson to his discovery?
Signup and view all the answers
How did J.J. Thomson's views differ from previous scientists'?
Signup and view all the answers
How did J.J. Thomson's atomic structure differ from today's?
Signup and view all the answers
When and where was Ernest Rutherford born?
Signup and view all the answers
What was Ernest Rutherford's contribution to atomic theory?
Signup and view all the answers
When did Ernest Rutherford make his discovery?
Signup and view all the answers
What experiments led Ernest Rutherford to his discovery?
Signup and view all the answers
How did Ernest Rutherford's views differ from previous scientists'?
Signup and view all the answers
How did Ernest Rutherford's atomic structure differ from today's?
Signup and view all the answers
When and where was Neils Bohr born?
Signup and view all the answers
What was Neils Bohr's contribution to atomic theory?
Signup and view all the answers
When did Neils Bohr make his discovery?
Signup and view all the answers
What experiment led Neils Bohr to his discovery?
Signup and view all the answers
How did Neils Bohr's views differ from previous scientists'?
Signup and view all the answers
How did Neils Bohr's atomic structure differ from today's?
Signup and view all the answers
When and where was James Chadwick born?
Signup and view all the answers
What was James Chadwick's contribution to atomic theory?
Signup and view all the answers
When did James Chadwick make his discovery?
Signup and view all the answers
What experiments led James Chadwick to his discovery?
Signup and view all the answers
How did James Chadwick's views differ from previous scientists'?
Signup and view all the answers
How did James Chadwick's atomic structure differ from today's?
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.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
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.