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Democritus
Democrtius is related to the invisiable solid sphere model. He founded the invisible solid sphere in 460BC. Democritus had a hypothesis that atoms cannot be destroyed, differ in size, shape and temperature, are always moving, and are invisible. -
Antoine Lavoisier
Antoine proposed the Combustion Theory which was based on sound mass measurements. He named oxygen. Also proposed the Law of Conversation of Mass which represents the beginning of modern chemistry. He is related to the Electron Cloud Model. -
John Dalton
His atomic theory (1903) said that elements consisted of tiny particles called atoms. It says an element is one of a kind (pure) because all atoms of an element are identical. All the atoms that make up the element have the same mass. All elements are different from each other because of differing masses. Everything is made of atoms. -
Michael Faraday
Michael Faraday, a British physicist, made one of the most significant discoveries that led to the idea that atoms had an electrical component. Faraday placed two opposite electrodes in a solution of water containing a dissolved compound. He observed that one of the elements of the dissolved compound accumulated on one electrode, and the other element was deposited on the opposite electrode. It was clear that electrical forces were responsible for the joining of atoms in compounds. -
JJ Thomson
Founded the plum pudding model of the atom who discovered the electron in 1897, was proposed in 1904 before the discovery of the atomic nucleus. The atom surrounded by positive charge to balance the electrons' negative charges, like negatively-charged "plums" surrounded by positively charged "pudding" -
Robert Milikan
Between 1908 and 1917, Robert Millikan measured the charge on an electron.Millikan was able to show that the charge on a drop was always a multiple of a small, but infinite value. Combining this value for the charge on a single electron with the charge to mass ratio for the electron confirms Thomson's hypothesis. He also got the Nobel Prize for Physics in 1923 for his measurement of the elementary electronic charge and for his work on the photoelectric effect. -
Ernest Rutherford
Created Planetary model. British physicist who became known as the father of nuclear physics. Worked with JJ Thomson. The model described the atom as a tiny, dense, positively charged nucleus, where all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun. -
Niels Bohr
Bohr is related to the electron cloud model but it is different from the older model by Niels Bohr. Bohr talked about electrons going around the nucleus in a fixed circle, in a similar way to the planets that go around the Sun. He introduced the idea that an electron can drop from a higher energy orbit to a lower one. Then it can emit a photon of discrete energy. This is the basis of quantum theory. -
Louis DeBrogile
Gained worldwide fame for his work on quantum theory. In his 1924 thesis, he found the wave nature of electrons and suggested that all matter have wave properties. He won the 1929 Nobel Prize for Physics. -
Marie and Pierre Curie
The work these two created dealt with changes in the atomic nucleus which lead to more modern understanding of the atom as an entity that can be divided to release energy. -
Henri Bequerel
Henri Bequerel Is know for his discovery of radioactivity. He later shared a noble prize with Marie and Pierre Curie for the discovery. Bequerel studied with his father for many years before his fathers death. His father was a huge I fluency on the discovery and helped Bequerel work his way to it. -
Max Planck
Max Planck was a German physicist, is best known as the originator of the quantum theory of energy.His work contributed significantly to the understanding of atomic and subatomic processes. Albert Einstein used Planck's quantum theory to describe the particle properties of light. Einstein demonstrated that electromagnetic radiation, including light, has the characteristics of both a wave and, consistent with Planck's theory, a particle. These particles were later called photons. In 1913, Niels -
Max Planck (cont.)
Bohr used Planck's theories to develop a new and more accurate model of the atom. Hence, the discovery’s made by Planck were guidelines for other scientists to lead to the full discovery of the atom, the truth behind it, and the known facts about their existence. -
Albert Einstein
Albert Einstein was the first person to show a way to probe the existence of atoms using an ordinary microscope. In 1905, Einstein was twenty-six years old and working in a doctors office. At this time he published his Special Theory of Relativity, which later lead to the General Theory of Relativity, which lead to his designation as the "father of modern physics." -
Earnest Schrodinger
ger:
Earnest Schrodinger took Niels Bohr’s discoveries one step further. (1926). Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. The atomic model he developed is called the quantum mechanical model. The quantum mechanical model does not define the exact path of an electron, unlike Niels. But, this predicts the odds of the location of the electron. -
James Chadwick
James Chadwick bombarded beryllium atoms with alpha particles with a nuetral electrical charge and the approximate mass of a proton. This particle became known as the neutron, and along with its discovery, a model became available to chemists. -
Lisa Meitner
Lisa Meitner met up with colleague Max Planck, Otto Hahn and her nephew Otto Frisch and together they researched about the beta and gamma rays with radioactivity during 1939. During one of their experiments, they discovered that if they combine barium and uranium they invented the acts of nuear fusion. Also, in one of their experiments they discovered how to split the nucleus of an atom which would later be known for nuclear uses such as the nuclear bomb. -
Otto Hahn
Otto Hahn worked under Sir William Ramsay, which lead to his discovery of theorem c and radioactinium. Then, working alongside Lise Meitner discovered mesothorium. While working with Meitner they discovered splitting of the atomic nucleus in uranium and Thorium. From 1939 on, Hahn continued to split atoms and other elements and see how they would arise through fusion. -
Glen T. Seaborg
Glen T. Seaborg synthesized 6 transuranium elements and suggested a change in the layout of the periodic table. Seaborg and his colleagues in the lab were responsible for the discoveries of over one hundred isotopes located within the period table. Seaborg is also the author of the actinide concept of heavy element electronic structure, which showed how the heavy elements fit into the Periodic Table and thus demonstrated their relationships to the other elements. -
Joseph Louis Proust
He first published Law of Definite Proportions in 1794. This law states that a compound is composed of exact proportions of elements by mass regardless of how the compound was created. He is related to the -
Aristotle
Aristotle came up with the planetary model in 350BC. The planetary model When the Atomic Theory was discovered, he didn't believe in it. He believed that all substances were made of fire, water, air, and earth. Born in 384 BC.
