-
500 BCE
The Alchemist
They developed the theory and thought that all metals are composed of sulfur and mercury to change base metals into gold. The Alchemy broke down the four basic elements of Earth, Fire, Wind, and water. They also contributed to the Atomic Theory, that is now the periodic table of Elements we use today. -
460 BCE
Democritus
Democritus a greek philosopher thought that they were substances called atoms and that they made up all material things, and thought they were unchangeable, always existed, and indestructible. He also introduced the idea of the atom and the Plum Pudding Model. In the model, the negative electrons are scattered throughout a sea of positive protons. -
427 BCE
Plato
Plato introduced the atomic theory in which ideal geometric forms would serve as atoms, which according then atoms broke down automatically into triangles, such that then the form elements had the following shapes: fire was tetrahedrom air was octahedron, water was icosahedron, and earth was a cube. -
384 BCE
Aristotle
He comprised that all elements of matter being composed of were fire, earth, air, and water. He only thought that those four were made of atoms. -
Robert Boyle
His contribution to the atomic theory was that he contributed to develop a definition of an element. He also contributed to the death of the four elements. He also called the group of atoms that he was studying molecules. -
Lavoiser
Antoine Lavoiser was a french chemist who through series of experiments discovered that the total mass of products with reactants in a chemical reactions is always the same. This then led to the theory of law of conservation of mass. -
John Dalton
John Dalton is most famous for introducing the Atomic Theory into the science of chemistry. his atomic theory was different in that he proposed that all matter was composed of atoms, along with indivisible and indestructible building blocks. Including all atoms of an element that were identical, different elements had atoms of different size and mass. He is also famous for coming up with the Solid Sphere of ''Billiard Ball'' Model. -
Dmitri Mendeleev
He is a Russian chemist that developed and made the periodic table of elements. He discovered that, when all of the known chemical elements were arranged in order, of increasing atomic weight, the final table displayed a repeating pattern of properties within groups of elements. When making the table he put the elements in order of their atomic weight. -
JJ Thomson
JJ is a British physicist that found out that atoms are made of smaller components. His finding paved the way scientists thought about the atom. They also wound up having had major ramifications for the field or array of physics. -
the Curies
French scientists and physicists Marie Curie and Pierre discovered the elements polonium and radium,, and that they were also highly radioactive. These two units naturally occur in uranium minerals. Marie named the word radioactive since the emission ionizing and penetrating rays by certain atoms. -
Einstein's Discovery of the Photoelectric Effect
Einstein discovered the principle of photoelectric effect is a phenomenon that electrically charged are released from or within material when it absorbs electromagnetic radiation. The effect is often defined as ejection of electrons from a metal plate when light falls on it. This is when electrons get excited. He assured that the kinetic energy of the ejected electron was equal to energy of the incident proton minus energy needed to remove the electron from the material, that is work function. -
Planks Quantum theory of Light
According to Planck's theory of quantum, the smallest amount of energy can be emitted and or absorbed in the form of electromagnetic radiation as known as quantum. Energy of the radiation is absorbed or emitted is directly proportional to the frequency of the radiation. -
Albert Einstein
He mathematically proved that atoms existed in 1905 and then helped revolutionize all sciences through the use of statistics and probability. Atomic theory says that any liquid is made up of molecules. Furthermore, these molecules are always in random, ceaseless motion that never stop. He was also the one who realized and developed the theory of Photoelectric Effect in Chemistry also came up with the formula for E=mc2, this formula means energy equals mass times the speed of light squared. -
Robert Millikan
He was an American physicist that won the Nobel peace prize. He is also known and credited for the discovery and finding of the negative charge and the electron. He is famous for the oil drop experiment. The oil drop experiment was testing for measuring the electron charge for the electron. This experiment showed that atoms have a small, and dense, positively charged nucleus. While the positively charged particles that are in the nucleus are called protons. -
Earnest Rutherford
Earnest was known in the science world for his studies about radioactivity and the atom. He found that there are two types of radiation, alpha and beta particles, that come from uranium. In addition he also found that the atom consists mostly of empty space, with its mass concentrated in a central positively charged nucleus. In his science career he also overturned Thomson's model of the atom. -
Neils Bohr
Neils Bohr proposed a model of the atom in which the electron was able to occupy only certain orbits around the nucleus. This atomic model was the first to use the quantum theory that the electrons were limited too specific orbits around the nucleus. -
Henry G. J. Mosely
He found a law named Moselys law, that discovered a relationship between the wavelength and atomic number. He also discovered how to solve for the atomic number for each atom. He later came out and posted that he discovered this by saying that the atomic number is the amount of positive charges in the atomic nucleus. -
Werner Heisenburg
He contributed to the atomic theory by formulating quantum mechanics with terms of matrices also in discovering the uncertainty principle, that in part states that a particle's position and momentum cannot both be known exactly. -
Schrodinger Equation
He assumed that all matter could be called or referred to as waves and atoms. He then came up and created a formula for a wave equation that accurately calculates the energy levels of electrons in atoms. He also took the Bohr model one step further, he used mathematic equations to help describe the chances of finding an electron in a certain position in an atom. -
James Chadwick
In 1932, James announced in his findings that he found that the core also found a new uncharged particle in the center of the atom. he would end up calling this a neutron, for its neutral charge. Therefore, he is the scientist that found the neutron.