-
400
Democritus
DemocritusDemocritus theory stated that ;
All things are composed of invisible tiny particles of matter, which can’t be destroyed. -
Period: 400 to
The dates of different theories
-
John Dalton
John DaltonStated a various amount of theories including:
• Describing tiny indivisible particles called atoms.
• Stating Atoms can’t be divided or destroyed.
• Stating Atoms can join together to form molecules.
• Stating Atoms of one element are all the same. -
J.J.Thomson
J.J. ThomsonConcluded theories stating:
• Atoms contain electrons, which have a negative charge.
• Atoms are solid with electrons and protons randomly placed through them. -
Ernest Rutherford
Ernest RutherfordThompson stated theories which concluded:
• Atoms have a dense nucleus which contains protons, and most of the rest is empty space.
• Electrons orbit around the nucleus like planets around the sun. -
Niels Bohr
Niels BohrStated refined theories which stated:
• Electrons are arranged in layers or shells around the nucleus.
• The shells have different energy levels, and electrons fill up the lowest levels first. -
James Chadwick
James ChadwickStated theory that:
• The nucleus also contains neutrons, which are unchanged particles with a similar mass to protons.
