Atomic Structure Scientists

Niels Bohr

- Danish Physicist famous for Atomic Structure Model - He discovered that electrons in atoms are arranged according to the energy level - Bohr's article on the atom appeared in the 13th edition of the Encyclopedia Britannica - Was one of the greatest physical chemists of the 20th century -He proposed the 'Solar System' model of atomic structure in which electrons orbit the central nucleus

Ernest Rutherford

Experiment - Gold Foil Experiment (used to prove the structure of an atom) (1911) He found that atoms positive nucleus and negative around the nucleus and most of it was empty space First to split an atom Converted nitrogen to oxygen Father of nuclear physics

JJ Thompson

Experiment: Did an experiment that showed that cathode rays could be deflected electrically Major Findings- Discovered electrons in 1897 Proposed Plum Pudding Model in 1904, was eventually disproved 1909

Robert Millikan

Experiment: The Oil drop experiment was an experiment performed by Robert Millikan and Harvey Fletcher in 1909 to measure the elementary electric charge (the change of the electron). The experiment entailed balancing the downward gravitational force with the upward drag and electric forces on tiny charged droplets of oil suspended between two metal electrodes. Major Findings: Robert Millikan determined the electrical charge of the electron through his experiment.

John Dalton

He created the Atomic Theory in 1803 which stated: 1. All matter was composed of small indivisible particles termed atoms 2. Atoms of a given element possess unique characteristics and weight 3. Three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules). First scientist to explain the behavior of atoms in terms of measurement of weight. He calculated atomic weights of elements and assembled them in a table which consisted of six elements namely hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus.

Democritus

Major Contribution: Discovered the atom and if it wasn't for Democritus there would be no atomic theory. Major Experiment: To find the atom, he broke a simple seashell in half and broke it until it was just left with a fine powder, then tried to break the powder but he could not, thus he discovered the atom. He discovered that not all atoms were the same size.