Hennig Brand was a merchant and alchemist in Hamburg, Germany. He discovered phosphorus around 1669. http://elements.vanderkrogt.net/element.php?sym=P
Antoine Lavoisier was a French nobleman prominent in the histories of chemistry and biology. He named both oxygen (1778) and hydrogen (1783) and also predicted silicon (1778). He helped construct the metric system, put together the first extensive list of elements, and helped to reform chemical nomenclature. http://moro.imss.fi.it/lavoisier/
John Dalton was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness (sometimes referred to as Daltonism, in his honour). Here's a free copy of a book coauthored by Dalton.
Johann Wolfgang Döbereiner was a German chemist who is best known for work that foreshadowed the periodic law for the chemical elements. http://chemed.chem.purdue.edu/genchem/history/dobereiner.html
Dmitri Mendeleev was a Russian chemist and inventor. He created the first version of the periodic table of elements. Using the table, he predicted the properties of elements yet to be discovered. http://www.chemheritage.org/discover/online-resources/chemistry-in-history/themes/the-path-to-the-periodic-table/meyer-and-mendeleev.aspx
Learn more about Mendeleev in this TED-Ed Lesson by Lou Serico, explaining the genius behind his version of the periodic table. http://ed.ted.com/lessons/the-genius-of-mendeleev-s-periodic-table-lou-serico