following the course of history

elliptical orbit

Apr 30, 1571

If Kepler had not discovered that the planets orbit around the sun in an elliptical orbit, I would have thought for a long time but that the planets rotate in around the sun circular.

the first protozoo

Sep 7, 1674

If Antonie van Leeuwenhoek had not had the interest to see beyond the eye seen, the first protozoo would not have discovered.

Comet

Apr 30, 1682

If Edmund Halley had not observed the sky would not have discovered the periodicity of comets with Halley's Comet

Gay-Lussac's Law)

Apr 30, 1805

If Joseph Gay-Lussac had not studied the behavior of gases, you would not have the law by which a gas is proportional expands its temperature (absolute) if the pressure is kept constant (Charles Law) and proportionally increased their pressure if volume remains constant (Gay-Lussac's Law).

Electrochemistry

Apr 30, 1807

If Humphry Davy had not made ​​a study of the electrolysis of various compounds, would not have discovered and named several pure chemical elements found on the periodic table

Urea

Apr 30, 1828

If the synthesis of urea would not carry out would not have been one of the first compounds synthesizing an organic compound through an inorganic compound

Benzene

Apr 30, 1865

If Kekule had not dreamed of the snake biting its tail, there would be a representative model for the structure of benzene

the periodic table

Mar 29, 1869

If Mendeleev had not posted the periodic table of the elements discovered, it would have taken to discover the order of the elements according to his or their orbital electronegativity.

radioactivity

Apr 30, 1898

If Ernest Rutherford and Marie and Pierre Curie had not investigated radioactive elements, now would not have the use of them for different raw materials and utilization as an energy source.

Complexometry

Apr 30, 1916

If Lewis had not created the atomic model of bonds  between electrons, there would be no concept Complexometry