-
Jan 1, 1000
Democritus (460 BC)
The theory Democritus had is that everything is composed of atoms, in which they cannot be divided futher, and were therfore indestructable and unlimited. -
Antoine Lavosier
He named oxygen and hydrogen and discovered oxygen's role in combustion. -
John Dalton
He created the Dalton Atomic Theory and theorized that an atom can not be created, destroyed nor divided and that atoms of different elements that are connected are called compounds. -
Dalton's Atomic Theory
Dalton's theory states that atoms can not be created destroyed or divided, in correspondance to Dalton's beleifs. -
Dmitri Mendeleev
He created the Periodic Table of Elements after theorizing how to organize the known elements. His system enabled him to predict the discovery and placement of elements such as Germanium. -
J.J. Thomson
He discovered the first evidence for isotopes of a stable element. J.J. Thomson also discovered the natural radioactivity of potassium and demonstrated that hydrogen had only a single electron per atom. -
Robert Andrew Millikan
He measured the charge on a single electron as well as wining the 1923 Nobel Prize for Physics. -
Ernest Rutherford
He created his namesake model of the atom and discovered the nucleus by the Gold Foil Experiment. -
Niels Bohr
He made many contributions to understanding atomic structure and quantum theory. He received the Nobel Prize in Physics in 1922. He also created his namesake model of the atom, in which he proposed that energy levels of electrons are discrete, and that the electrons revolve in stable orbits around the nucleus. -
Erwin Schrödinger
He developed a number of results in the field of quantum theory, which created the basis of wave mechanics. He also created the quantum mechanical model for the atom. -
Henry Moseley
He came up with chemical concept of the atomic number. He theorized that the number of positive charges (protons) were equal to its atomic number. -
Sir James Chadwick
He won the 1935 Nobel Prize in physics for his discovery of the neutron in 1932. He also inspired the U.S. government to begin serious atomic bomb research efforts. -
Cathode Ray Tube
It's a vacuum tube containing one or more electron guns meant to accelerate and deflect the electron beams onto the screen to create the images, which a fluorescent screen is used to view images. -
Plum Pudding Model
In this model, the atom is composed of electrons surrounded by a soup of positive charges to balance the electrons' negative charges -
Gold Foil Experiment
The gold foil experiment showed that the plum pudding model of the atom was wrong. This was because sometimes the alpha particles awould bounce back when hitting the gold sheet, proving most of the atom was empty space. This eventually lead to the discovery of a nucleus. -
Rutherford Model
Ernest Rutherford's model, comprised of a nucleus of positively charged particles with electrons around it. -
Bohr Planetary Model
States the atom is a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus. -
Electron Cloud
A way to describe the location of electrons when orbiting the nucleus. (Different from Bohr's model of the atom in refference to the electrons) -
Quantum Mechanical Model
A model of the atom by Erwin Schrödinger, allowing him to theorize the location of an electron.
