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400
Democritus 400 BC (Greek Era)
Democritus lived a long time ago, from 460 BC to 370 BC in Greece. He was an influential philosopher. Everything is made up of atoms. Atoms are indestructible -
Isaac Newton
Isaac Newton lived in England from 1642-1727. He created the 3 laws of motion. Formulated a theory of light. Atoms are held together with forces. Suggested a mechanical universe with small masses in motion. Matter is formed of soli impenetrable particles. -
John Daltion
John Dalton lived from 1766-1844. All matter is made up of atoms. Atoms can’t be made or destroyed. Different elements have different types of atoms. Compounds are made from atoms of the constituent elements. Atoms of different elements could be distinguished by differences in their weights. -
Robert Brown
Robert Brown did an experiment with pollen grains in water and observed how they moved. He noticed they were bouncing around and moving almost as if they were alive. The molecules and atoms in the water were actually pushing the pollen grains around. This theory is called the Brownian Motion. -
Michael Faraday
Michael Faraday was a British physicist in the 1830s. Atoms have an electrical component. Electrical forces were responsible for the joining of atoms in compounds. -
Dmitri Mendeleev
Came up with the idea that he could arrange the elements in order according to their atomic mass. Made his discovery in 1869.This new formula and discovery helps to piece together the modern periodic table which is an amazing tool when it comes to science. -
James Maxwell
He was trying to understand the theory of electricity and magnetism. After developing this he pointed the way to electromagnetic radiation. His research and findings help us in our everyday lives. With radios, television, radar, microwaves and even thermal imaging. He made his discovery in 1873. -
Wilhelm Roentgen
Wilhelm was experimenting with cathode rays and discovered new rays. He discovered the rays left an image on the plate. He discovered what we now know as x-rays. -
J.J Thomson
Joseph John Thomson lived from 1856-1940. Discovered the electron in a series of experiments. Later he estimated the value of the charge itself. Used rays, electrically charged plates and magnets to discover these things. -
Albert Einstein
Albert Einstein was German and lived from 1879 – 1955 and died at the age of 76. Matter and energy as exchangeable. Theory of relativity. Even pure energy has to behave in some ways like mass. Therefore the gravitation force of the sun could bend light. -
Robert Millikan
- Made his contributions in 1909.- He discovered accurate values for the mass and charge of electrons. - Used a drop of oil to observe its terminal velocity. - Finding the mass of electrons has helped move the atomic model along and has proven very helpful.
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Ernesht Rutherford
He was born on August 30th 1871 in New Zealand. His theory was based around the idea that the atom has a central positive nucleus surrounded by negative electrons that orbited it. Most of the mass of the atom was contained in the small nucleus and the rest was mostly empty space. Nucleus is described as tiny, dense and positively charged. Electrons behave much like planets do when orbiting the sun. -
Niels Bohr
Lived from 1885 – 1962. His atomic model showing a positively charged nucleus, which contains some protons and neutrons. Negatively charged electrons also surround the nucleus. His model is very similar to the solar system. Electro static force providing attraction force rather then gravity force. -
Werner Heisenberg
Lived from 1901 – 1976. His most memorable discovery was the Uncertainty Principle. In this theory he stats that electrons do not travel in neat and organised orbits. And that electrons containing photons with then change momentum and physics. He calculated the behaviour of electrons and discovered subatomic particles. -
Erwin Schrodinger
In 1926 Erwin Schrodinger created a new model of the atom. The advantage of this model is that it consists of mathematical equations. That electrons are like waves. His theory tries to describe the regions in space where you can find electrons. Is a model to show the distribution of electrons in an atom. -
James Chadwick
Found that some unknown particles are actually uncharged neutrons and have roughly the same mass as protons. This radiation is uncharged. His atomic model includes neutrons within the nucleus to explain why the mass of an atom exceeds its number of protons. Made his discovery in 1932.
