Planck's Constant -> 6.626 x 10^34
Also the idea of Quanta's, further researched by Einstien. :D
Atomic Theory
I don't know of atomic theory, but he came up with the idea that light energy acted like packetts of energy that he called photons. Thru some theoretical calculations he came up with Plank's constant that deals with the energy of different wavelengths of light.
Dalton's atomic theory was a major contribution to discover the atomic structure in despite of been completely counterproved.
Two related questions (completed with answers) should be followed.Cf 'Related questions' in the link below this answer.
The cell theory
Mendel
Dalton's Atomic Theory 1) All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms.
Charles Darwin was a naturalist. His major contribution to science was the Theory of Evolution.
They contributed the atomic bomb which had a major impact on the citizens of Hiroshima and Nagasaki.
Mendel
Mendel
His theory of "Natural Selection" (Evolution) .