-
322
Aristotle died.
-
370
BC Democritus died.
Democritus died. Democritus was criticized a lot through his life for his theory, for reasons because he didn’t explain the initial cause of the atoms moving. -
420
BC Leucippus died.
-
460
BC, Democritus was born. Democritus made several claims about atoms.
Democritus was born. In his life Democritus said everything is made up of atoms, which are physical but not geometrically indivisible. He also said between atoms lays empty space, they are indestructible, are always in motion and there are infinite atoms. -
Lavoisier was born.
-
John Dalton was born.
Dalton was born. Throughout Daltons life he discovered many things about atoms such as all matter is made up of atoms, which are indivisible and indestructible, atoms of a given element have the same mass and properties, a combination of 2 or more different kinds of atoms is a compound and a chemical reaction is a rearrangement of atoms. -
Robbert Brown was born.
-
Lavoisier discovered several things such as...
Lavoisier began the first law of conservation of mass. He found that although matter changes in shape it always weighs the same. He also named both hydrogen and oxygen, helped to construct the metric system and helped to form the first list of elements. -
Faraday was born.
-
Lavoisier died.
-
Robert Brown made a discovery...
He discovered that small particles of inorganic materials like, carbon and metals display Brownian motion, this proved important to the development of the atomic theory.He also gave the name nucleus, to the nucleus! -
Faraday.
Faraday used electrolysis to split molecules with electricity and developed electrolysis laws. He made a significant discovery leading to the idea atoms had an electrical component. After experiments it became clear to Faraday that electrical forces were responsible for the joining of atoms in compounds. -
Mendeleev was born
-
John Dalton died.
Dalton died. Not all scientists agreed with Daltons theory’s, and it took a long time before it was known as an important theory. -
Thomson was born.
-
Robbert Brown died
-
Faraday died.
-
Mendeleev created the periodic table.
Mendeleev arranged the elements with similar properties into 7 different groups. When doing this he discovered that the properties of elements are periodic functions of their atomic weights. This is now known as the periodic law. -
Mendeleev further developed his periodic table.
After Mendeleev made the periodic law he predicted 3 new elements and several of their properties including density, radii and also combining rations with oxygen among others. The 3 new elements he predicted were eka-aluminum, eka-boron and eka-silicon. -
Rutherford was born.
-
Bohr was born.
-
Schrodinger was born.
-
Chadwick was born.
-
Thomson discovered the electron.
Thomson discovered the electron after a series of experiments. He said the electrons had a very large charge to mass ratio. -
Fermi was born.
-
Heisenberg was born.
-
Thomson's atomic model
Thomson’s model of the atom he suggested was a sphere made up of positive matter where the electrons are positioned by electrostatic forces. -
Mendeleev died.
-
Rutherfords atomic theory
Rutherford’s atomic theory descries the atom as having a central positive nucleus, which is surrounded by, negative orbiting electrons. His theory suggests that most of the atoms mass is in the nucleus and other than the tiny electrons it is surrounded by empty space. Rutherford used his gold foil experiment to come up with his atomic theory. Rutherford would fling radioactive particles at the gold foil, finding that about 1 in 8000 were deflected. This is how he came up with the theory that mo -
Bohr develped the quantizized shell.
Bohr published his quantized shell model of the atom, which was a modification of the earlier Rutherford model. Bohrs model explains how electrons can have stable orbits around the nucleus. In Rutherford’s model the electrons were unstable and moved on a curved path and would have lost energy spiralling into the nucleus. Bohr modified Rutherford’s model and stated that electrons move in orbits of fixed size and energy making them stable. -
Rutherford discovered the proton.
Rutherford discovered the proton a positively charged particle within the atom's nucleus. But they and other researchers were finding that the proton did not seem to be the only particle in the nucleus. -
Schrodinger took the Bohr atomic model and modified it.
Schrodinger took the Bohr atomic model and modified it. Schrodinger’s atomic model is known as the quantum mechanical model, it doesn’t show the exact path of the electron but it predicts the location of the electron. -
Fermi studdied neutrons.
Fermi studied the theory of neutrons. Using this theory they slowed down the neutrons and produced a new product when using the neutrons on uranium. This later became recognised as splitting of the uranium atoms. -
Chadwick discovered the neutron
Chadwick discovered the neutron. After Rutherford discovered the proton he and other researches where questioning wether the proton was the only particle inside the atom. Chadwick realised that the atomic number was less than the atomic mass meaning that there was something other than the nucleus and the protons in the atom adding to the mass. This discovery of Chadwick’s enhanced and accelerated nuclear physics a lot. -
Fermi was incharge of the first controlled chain reaction.
Fermi was in charge of the first controlled chain reaction by releasing energy from the atoms nucleus. -
Rutherford died.
-
Thomson died.
-
Fermi died.
-
Schrodinger died.
-
Bohr died.
-
Chadwick died.
-
Heisenberg died.
-
Heisenberg atomic theory.
Heisenberg said electrons don’t travel in neat orbits; this is one of his most significant discoveries. He also contributed to the atomic theory by calculating the behaviour of electrons and subatomic particles making up the atom. Instead of using scientific terms Heisenberg brought math into the patterns of an atoms electrons, helping scientists compare by the movement of electrons and how many electrons atoms contain. Heisenberg contributed to the atomic theory with quantum mechanics used for -
Aristotle was born, Aristotle believed all things were made of matter and essence.
Aristotle was born, Aristotle believed all things were made of matter and essence. Aristotle thought organisms of the same species were made of the same but different matter. Aristotle believed matter could be broken down into the four elements. His beliefs were accepted over Democritus’s. -
BC Leucippus was born.
Leucippus was born. Leucippus worked with Democritus and is thought to have come up with the theory that the universe is made up of atoms and contains the solid and the void. Together the solid and the void make up the universe.
