John Dalton

John Dalton was an English-born scientist who lived between 1766 and 1844. He earnt his living in teaching and giving lectures, and started school around the age of 12. He was a meterologist who switched upon seeing the "applications for chemistry of his ideas about the atmosphere." He was first to suggest the Atomic theory, which proposed the following:

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).

  "Dalton's theory" can be found in New System of Chemical Philosophy.

Glenn Seaborg

Glenn Seaborg was an American scientist born in Ishpeming, Michigan. His family was poor and he served his college days working a number of jobs - a stevedore, fruit-packer and laboratory assistant. After his graduation at the University of California (in 1934), he took his education further by completing his Ph.D. at Berkeley. In the event of the second world war - he worked at the University of Chicago's Metallurgical Laboratory. There,  he helped to develop plutonium in "uranium reactors." Later, after being appointed a professor of chemistry at the University of California (in 1946) he received a Nobel Prize for his discovery of plutonium. He is notable for being appointed chairman of the Atomic Energy Commission by President John Kennedy himself. 

Henry Gwyn Jeffreys Moseley

Henry Moseley was born on November 23rd in 1887 and was an English physicist. He was most notable for sorting the chemical elements on the periodic table and the concept of the Atomic number. He redefined the previous idea of the Atomic number and made a great contribution to science. He was also the inventor of the X-ray spectrometer. He later died on the 10th of August 1915.

Dmitri Ivanovich Mendeleev

Dmitri Ivanovich Mendeleev, born 1834 in the village of Verkhnie Aremzyani, was a Russian chemist, and the first to event the world-known periodic table of elements, which serves a distinctive and useful purpose in science today. Using his table, not only did he account for the elements which exisited in his time, but also elements and their properties yet to be discovered.  After becoming a teacher, Mendeleev penned Principles of Chemistry, the most clear-cut and definitive textbook of his time,and in 1869, presented his new information to the Russian Chemical Society, in a presentation entitled The Dependence between the Properties of the Atomic Weights of the Elements, where he desribed the elements in detail. Months after publishing his table, a seperate scientist by the name of Meyer came out with a design virtually the same, although there is some speculation, Dmitri Ivanovich Mendeleev is more formally known as the creator of the Periodic Table.

Mendeleev's Periodic Table

Aristotle

Aristotle

Aristotle, the well known philosopher, was born in Ancient Greece around 384 BC. A student of Plato and the teacher of Alexander the Great. Also a writer of many talents, who wrote across genres of physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology. He had a long-lasting influence on the development of all Western philosophy. He died at the age of 62, and it is believed most of his recollections and writings are now lost, and only roughly one-third of the original works have survived.

Democritus

Democritus of Abdera

Democritus was a scientist of Greek origin, born in Abdera in 460 B.C to a family of great wealth and nobility. Democritus and philosipher Leucippus, were the first to propose the idea that everything was made up of Atoms. And that such atoms were indestructable, and are continously moving. That there are an infinate amount of atoms, that differ in size and shape. An idea that continues to exisit today. Democritus was also one of the 3 to put forward the earliest views on the shapes and connectivity of the atom. He is considered widely to be"The father of modern science."