-
Period: 450 to
Beginning
-
John Dalton
John Dalton found that when elements such as hydrogen and oxygen combine, they always combine in certain ratios. His theory was that all matter is made of individual particles called atoms, which cannot be divided, he also thought that a chemical reaction was a rearrangement of atoms.
Dalton's theory was supported by other scientists and became the theoretical foundation in chemistry. -
JJ Thomson
Thomson did expirements with glowing gases of beams and showed that charged objects; He showed that charged objects could deflect the beam. Thomson believed that all matter is made of individual particles called atoms, which cannot be divided. He also discovered the electron in 1906. His discovery and theory was proved through his expirements. -
Marie Curie
Marie hypothesized that radation doesn't come from the molecule, it comes from the atom. Marie Curie had a theory of radioactivity, that theory was that radioactivity broke down atoms, in return released radiation in energy and subatomic particles. She found this theory by doing different expirements.
Marie Curie also faced many struggles along with becoming a atomic scientist, she had a family along the way, thus she had to be a mother, and wife. She also had to be a nurse during WW1. -
Max Planck
He became considered the inventor of the quantom theory. Planck's law of black body radiation was the basis for quantom theory which meant the amount of electromagnetic energy with a certain wavelength radiated by a black body in thermal equilibrium.
Planck's life was tough, his wife & daughters died in childbirth, his sons died during WW1 and Erwin's (his friend) death "destroyed" Planck's will to live. Planck's theory was proved by his many expirements. -
Ernest Rutherford
Rutherford fired atoms through gold foil and found out that atoms have parts of atoms that are free and some parts that are solid. He fould that atoms are made of a thick-heavy mass part and a thin - low mass part, but it is mainly empty space. Rutherford's model of the atom has electrons circuling around the nucleus. He went to win a noble peace prize due to his theory and expirement of the atom. -
Neils Bohr
Bohr's theory was that electrons have certain amounts of energy. Electrons surrounded the nucleus in rings and they can jump from a level to another. He compared the electron function to the planets orbiting around the sun. The problems with Bohr's theory was that it violated the Heisenberg Uncertainty Principle. The theory considers electrons to have a known radius and orbit. -
James Chadwick
Chadwick proved the existence of neutrons in atoms. His theory was that the nuetral part of atoms was called a nuetron, and it was a key part in splitting atoms. Chadwick was able to help other scientists understand the structure of an atoms nucleus. During WW1 James Chadwick was imprisoned in a german camp, but while being imprisoned, he worked on his theory of the atom. -
Hideki Yukawa
Hideki Yukawa had a theory of mesons ( hadronic subatomic particles ). The theory explained the interaction of nuetrons and protons. In 1936 his theory was proved because Carl David Anderson & others observed charged pi mesons. The mechanisms of nuclear binding and decay became problems in the theory, but it was proved after the observation(s). -
Democritus - BCE
Democritus believed that all matter weas made of out substances that could not be divided. He was one of the creaters of the atom, and named it an "atom" because of the greek word "Atomos", which means indivisble. Though Democritus was one of the creaters of the atom, his theory was often questioned.
