Atomic Time Line

Scientist-Year of Discovery

Antoine Lavoisier-1777
Charles Coulomb-1784
John Dalton-1798
William Crookes-1870
JJ Thompson-1898
Wilhelm Becquerel-1896
Marie Curie-1896
Ernest Rutherford-1909
Albert Einstein-1905
Robert Millikan-1908
Niels Bohr-1913
Erwin Schrodinger-1926
Werner Heisenberg-
James Chadwick-1931

Videos of atomic Time Line


History of the Atom


Died- 370BC
Democritus, one of the leading scientists of his time, lived in the Greek city state called Abdera. Little is known about Democritus except from the transcripts that Aristotle and other wrote about. He learned most of what he new when he was an apprentice to another scientist who went by the name Leucippus. Democritus began to study what many scientists referred to as the "void". Scientists of the time believed that there was empty space where nothing could be seen. but Democritus did not believe this theory. He thought that within the void there was something invisible to the naked eye, he gave it the name atomos, meaning invisible, know called atom. Democritus theorized that if you continued to break down matter it would eventual be broken down into individual atoms.



aristotle.jpgAristotle was born in Stagira in northern Greece. He spent twenty years of his life studying under Plato. After Plato’s death Aristotle returned to Macedonia, where he supposedly helped educate Alexander the great. With Alexander permission Aristotle opened up his own teaching school, spending most of the rest of his life researching, teaching and writing.

Alelemsquare.gifthough Aristotle made many great discoveries one of his most significant was his theory of matter. He thought that there were only four elements in existence; they were fire, air, water and earth. He said all matter is made up of these four elements and that these elements and four properties. These properties were hot, cold, dry and wet.

Antoine Lavoisier
Lavoisier was born in Paris to a wealthy family. With the death of his mother he inherited a large fortune at the young age of five. He attended College Mazarin from 1754 to 1761, he studied chemistry, botany, astronomy. and mathematics.From 1761 to 1763 he studied law at the University of paris. He always had a deep love for science which was mainly influenced by etienne Condillac, a prominent French scholar.

Lavoisier did most of his research on gases water and combustion. He demonstrated how oxygen was a key component in rusting metal. He also showed how oxygen was used in animal and plant respiration. Lavoisier conducted experiments that showed that respiration was a slow combustion of organic materials using inhaled oxygen. With this Lavoisier disproved the phlogiston theory, which stated when burned a substance called phlogiston is given off. He also discovered that when hydrogen and oxygen were combined it formed a dew, which seemed to be water. Although he was charged with taken another scientist work and elaborating on it.

Devise Lavoisier used in Discovery of Combustion


Charles Coulomb

Coulomb was born in Angouleme France. When he was five his family moved to Paris, and there he studied at the College des Quatre-Nations. As a result of his studies of ma thematic at the school, he decided he wanted to peruse mathematics in similar subjects. He went on to military school and after graduation was assigned to design Fort Bourbon.

He is said to have discovered the inverse relationship of electric charges, for this discovery they named the discovery Coulomb's law. he also pioneered and wrote a book on torsion balance. With his torsion balance he was able to experiment on the distribution of a charge on a surface, on the laws of electrical and magnetic forces, and the mathematical theory. he had a total of six publications the first tell how to use the torsion balance. the second explains the repulsion by attraction of magnetic and eclectic fields. His third stated the quantity of electricity is lost over a period of time. His fourth principal is on how Leticia fluid flows between two objects. His fifth stated that electric fluid divides itself between conducting objects brought into contact, and the distribution of this fluid on the different parts of the surface of this object. His sixth and final book stated that more research into the distribution of the electric fluid between several conductors, and the determination of electric density at different points on the surface of these bodies was to be done.
Torsion Balance

John Dalton(aka D Reich)

Dalton was born in Eaglesfield, England. At the age of fifteen he helped his brother run a Quaker school. It is believed that at an early age Dalton wanted to study law or medicine but was not allowed to by his family. He became professor of mathematics at a school in Manchester but left the school to become a private tutor and make more money.

During Dalton's time Democritus' theory of the atom was not widely accepted. Dalton swayed people's opinion about atomic structure with hios five main theories about atoms. His first theory was that elements are made of tiny particles called atoms. His second theory stated all the atoms of a given element are identical. Another of his theories stated atoms of one element are different from those of another element, and that different elements can distinguished by their given weights. Dalton's fourth theory of atoms was two different elements' atoms can combine to form chemical compounds, and that a given compound always has the same number of types of atoms. Dalton's fifth and final theory stated that atoms cannot be created, made smaller, destroyed by chemical means; the chemical process only changes the grouping of atoms.

Dalton's Periodic Table


William Crookes


Crookes was born in London, and was the oldest son of Joseph Crookes. He received some education of science while attending grammar school at Chippenhm, Wiltshire. But he really began his career in science when he, at only fifteen, entered the Royal College of Chemistry, in London.

Crookes is best known for his discovery of cathode Rays. He made the discovery by using a vacuum tube made by Heinrich Geissler. Crooks created a vacuum which had zinc sulfide around the side of one end, and a metal cathode imbedded in the other end. In the middle of the tube he placed a metal anode in the shape of a cross. When he ran electricity through the tube and image of the cross appeared and the zinc sulfide glowed. He hypothesized that these must be rays that came from that cathode and made the zinc sulfide glow. He gave these rays the name cathode rays.

J.J. Thompson

J.J. Thompson was born in Manchester England. Thompson lost his father at the age of sixteen. In 1870 he studied engineering at Owens College in Manchester. After Owens College he went onto study at Trinity College in 1876.In 1880 he obtained a Bachelors in mathematics and a Masters in 1883.He taught at Cavendish, teaching physics. For his work of conduction of electricity in gases he won the Noble Prize in 1906.he became a knight in 1908 and was shortly given the title of Order of merit in 1912. He eventually became the Master of Trinity College until his death.

JJ Thompson was most known for his experiments with rays. Thompson took cathode rays and cathode ray tubes, which lead to the discovery of electrons and subatomic particles. In his first experiment he wanted to see if he could remove the negative charge by means of magnetism. he found that the rays would bend but the negative charge was inseparable. In his second experiment he tried to bend rays with an electrical charge.This time he used a cathode ray tube with an almost perfect vacuum. He discovered that the rays did bend towards the negative charge. In his final experiment he wanted to measure the mass to charge ratio. He did this by how mush they deflected and the amount of energy they had. What he concluded was that atoms are actually divisible.

Plum Pudding Model


Wilhelm C Roentgen

Rontgen was born in Rhenish Prussia. In 1884 he moved to the Netherlands. He attended school at the Institute of Martinus Herman van Doorm. After that school he then attended Utrecht Technical School from 1861 to 1863. He was later expelled for refusing to give up one of his friends who were caught do something bad. In 1869 he graduated the University of Zurich with a PhD in mechanical engineering.

Rontgen is most known for his discovery of X-rays. He was using a vacuumed Leonard’s tube with cathode rays. When he put a charge through the tube he noticed that the rays passed through every day materials and lit up on a surface coated with barium platinocyanide. He discovered that the rays went straight through flesh but were reflected when it hit bone.


Henri Becquerel
Born -1852

Becquerel was born in Paris. France and was a third generation scientist. He studied science at the Ecole Polytechnique and engineering at Ecole des Ponts et Chaussees. In 1903 he shared the Nobel Prize whit Pierre and Marie Curie for his discovery of spontaneous radioactivity.

He is best known for his accidental discovery of radioactivity. He was experimenting with phosphorescence in uranium salts when he made the discovery. He was wrapping a fluorescent substance, potassium uranyl sulfate, in photographic plates. He thought he needed bright sunlight to conduct the experiment. Prior to conducting the experiment though he found the plates were fully exposed. It lead him to investigate spontaneous emission of nuclear radiation.
What Becquerel saw


Marie Curie
Marie Curie was born and raised in Poland but eventually obtained her French citizenship . In 1891 she accompanied her older sister to study in Paris. She was married to Pierre Curie who won an noble Prize. Even though she did most of her studies in France she never lost a sense of where she came from. The first element she discovered she named polonium for her home country of Poland.

Marie Curie is best known for her discovery of radioactivity, which is a process in isolating radioactive isotopes.With this discovery Marie and her husband suggested radioactivity could be used to battle cancers. Curie also discovered two new elements which she named radium and polonium. It is in the way she discovered them which is amazing.They were given tons of soil in which they thought a radiative element lay. They then began the tireless process of sifting each radioactive element out. Both Marie and her husband felt that they need a sufficient amount along with a weight for
people to accept it. They found that this new element gave off heat and light even in s dark room. They were dealing with radioactivity.


Ernest Rutherford

Ernest Rutherford was born in Nelson, New Zealand. He was the fourth child out of seven. He received his early education at Government schools and at 16 he entered collegiate school. He was awarded a University scholarship and he went to study at the University of New Zealand. He graduated in 1893 with a double first in mathematics and Physical Science. He then got a scholarship in 1897 which allowed him to study at Trinity College.

He is most famous for his discovery of beta rays which were emitted from radium. He did this by his famous gold foil experiment. He fired radioactive particles through gold foil. He found that some of the rays bounced back. He theorized that the atom must have mostly empty space while only a tiny percent is made up of solid matter.

Gold Foil Experiment


Albert Einstein

Einstein was born in Wurttemberg, Germany. Six weeks after his birth him and his family moved to Munich, were years later he would begin his schooling at the Luitpold Gymnasium. He later continued his education at Aarau, Switzerland. In 1896 he entered the Swiss federal Polytechnic School in Zurich and was trained in physics and mathematics. In 1933 he moved to the US to avoid the conflict in Germany. He became a professor of Theoretical Physics at Princeton.
He did most of his remarkable work while working at the patent office and in his spare time. His greatest discovery was his theory of relativity. He attempted to reconcile the laws of mechanics with the laws of the electromagnetic field. With this he explained the Brownian movement of molecules. He also investigated the thermal properties of light with low radiation density, which led to the foundation of the photon theory of light.

Rule of Relativity


Robert Millikan

Device Millikan used In Oil Drop Experiment



Robert Millikan was born in Morrison, Ill to a reverend. He attended Maquoketa High School. After working for a short time he attended Oberlin College in 1886. His favorite subjects were Greek and math. After school though he took a job teaching physics and that is where his love grew for physics. In 1893 after getting his masters in physics he appointed Fellow of Physics at Columbia University. He later got his PhD.

Millikan made a number of great discoveries mostly in the fields of electricity, optics and molecular physics. His first breakthrough was determining the charge of an electron, through the “falling drop method”. He also stated that all electrons have the same charge. He also proved Einstein’s photoelectric equation. He also studied the spectrum or rays between ultraviolet and X-rays. Doing this he lowered the spectrum. His studies of particles entering the earth’s atmosphere and his investigation on electrical phenomena, lead him to study cosmic radiation. During WW1 he was a big part in developing anti-submarine and meterologic devises.

Neils Bohrmoz-screenshot-4.jpg225px-Niels_Bohr.jpg
Born 1885
Died 1962

Bohr was born in Copenhagen, Denmark on October 7, 1885. Bohr attended the University of Copenhagen in 1911. Following his schooling he traveled to Manchester England to learn and study from the great chemist Ernest Rutherford. He is most noted for his contribution to the atomic theory. In 1922 he won the Nobel Prize for physics. He won the award for his breakthrough work on the structure of the little understood atom.
Bohr is mostly known for his work with the atomic structure. In 1913 he published his theory which was closely linked to one of Rutherford’s theories. Bohr elaborated on Rutherford’s idea of atoms consisting of a positively charged nucleus and negatively charged electrons. Bohr suggested that travel in orbits that get continuously bigger as they get further away from the nucleus. Bohr also theorized that the very outer lawyer orbit could hold more electrons. With this Bohr believed that an atom’s outer orbits are determined it chemical properties. Bohr also found when the electrons moved within orbits radiation was created, and light is created.

Bohr's Model

Erwin Schrodinger
Schrodinger was born in Vienna, Austria. He learned both German and English at the same time because both were spoken at his household. His mother was English and his father was Austrian. In 1898 he attended the Akademisches Gymnasium. Between 1906 and 1910 he studied in Vienna under Franz Seafin Exner and Friedrich Hasenohrl. After his studies with both men he participated in experiments with Friedrich Kohlrausch. In 1911 Schrodinger became an assistant to Exner. Between 1914 and 1918 he participated in war as a commissioned officer in the Austrian Artillery.

He is best known for his development of wave mechanics and his equation called Schrodinger equation. In the equation he gave “derivation” of the wave equation for time independent systems. He also proved that it gave correct energy eigenvalues for the hydrogen-like atom. Schrodinger’s paper is celebrated as one of the greatest achievements of the 21st century, and created a revolution in quantum mechanics. In his second paper showed the quantum harmonic oscillator, the rigid rotor and the diatomic molecule, and a new derivation of the Schrodinger equation. In his third paper he described the Stark effect and how his approach was equal to that of Heisenberg. In his fourth paper he described how to use the equation when time changed.

Model of Wave Mechanics

Werner Heisenberg

Heisenberg studied at Ludwig-Maximilians University in Munich. There he studied physics and mathematics from 1920 to 1923. He received his doctorate in 1923. When Hitler came to power Heisenberg was forced into hiding, and was being chased by the SS. Near the end of WW2 he was one of ten scientists arrested by the Americans.

Heisenberg made a breakthrough in quantum mechanics with his matrix formulation in 1925. He compiled the equation on what he observed, which is the radiation emitted by an atom. He tried to use the equation to find the location of an electron in an atom at a specific time, he was never really successful. He was also one of the nine researchers in German nuclear energy project. With this equation he bridged the gap from mathematics and physics.

Quantum Mechanics Equation


James Chadwick

James.jpgJames was born in Cheshire, England. He went to college at both Manchester and Cambridge universities. In 1913 he worked at the Technical University of Berlin. One of the famous chemists he worked with was Ernest Rutherford.

Chadwick is best known for his discovery in 1932 with his discovery of the neutral neutron. He realized that there was not just protons and electrons in atoms, but a particle that had no charge. He found that it was much bigger than the electron it had no charge. So it wasn't effected by charges around it. He discovered that the neutron could be used to penetrate and split other atom's nuclei. With this discovery the fission of Uranium 235 and the atomic bomb where made plausible. With this discovery he was awarded the Nobel Prize for Physics in 1935.
Chadwick model of Electron