-
400 BCE
Democritus Defines Atoms
About 400BC a Greek philosopher named Democritus tried to divide matter over and over again. He said that there would be a point when it cannot be divided anymore. He named the particles atomos, that means uncuttable. A fun fact about Democritus is he was called the laughing philosopher because he was always so happy at work. -
400 BCE
Democritus Model
-
John Dalton and the First Atom Model
John Dalton liked to study Chemistry and he was a teacher from the United Kingdom. He started teaching when he was only 12 years old. He took really good notes and was able to make the first model of the atom using his notes. He did a lot of experiments examining chemical reactions. He believed atoms were hard and round and that they were indestructible. -
John Dalton's Model
-
J.J. Thomson Discovers Electrons
J. J. Thomson grew up in the United Kingdom. He discovered and named the negatively charged particles in an atom electrons. He created a model of the atom called the raisin bun. He believed the negative charged particles were scattered throughout a ball made of positive charged particles. The model looked like a ball of dough and the electrons were the raisins. -
J.J. Thomson Model
-
Ernest Rutherford Names Parts of the Atom
Ernest Rutherford was born in New Zealand but he died in the United Kingdom. He did many experiments but his most popular one was shooting a beam of particles at gold foil. It helped him discover that an atom is mostly empty space. The electrons move around dense, positive charged center and he named it the nucleus. He also named the positive particles protons. Sadly, he died due to a strangulated hernia in 1937. -
Ernest Rutherford Model
-
Niels Bohr Defines Energy Levels in an Atom
Niels Bohr was from Denmark and he studied the discoveries of Ernest Rutherford. He used that information to prove electrons move around the nucleus at different energy levels. He compared them to planets orbiting the sun. They all had different levels of energy, the closer ones had less and the further ones had more. In 1922 he won the Nobel Peace Prize. -
Niels Bohr's Model
-
Erwin Schrodinger
-
Modern Cloud Model
-
Period: to
Erwin Schrodinger & Werner Heisenberg develop the Modern Cloud Model
Both Schrodinger & Heisenberg had a part in developing the modern "cloud" model, or the quantum mechanical model. They both used mathematics as a way to prove you could only find the probability of the location of an electron. Schrodinger said they moved in waves. They were from different places but used the research to form the new model. Schrodinger was from Austria and Heisenberg was from Germany. -
Werner Heisenberg
