Dalton, J.J. Thomson, and Rutherford
Dalton
A chemical reaction is a rearrangement of atoms.
Dalton
All atoms of a given element are identical in mass and properties.
Dalton
All matter is made of atoms. Atoms are indivisible and indestructible.
Dalton
Compounds are formed by a combination of two or more different kinds of atoms.
J.J. Thomson
He demonstrated that cathode rays were negatively charged. In addition, he also studied positively charged particles in neon gas and realized that the accepted model of an atom did not account for negatively or positively charged particles.
Ernest Rutherford
He discovered alpha and beta rays, set forth the laws of radioactive decay, and identified alpha particles as helium nuclei.
J.J. Thomson
He discovered the electron by experimenting with a Crookes, or cathode ray, tube.
Ernest Rutherford
He thus developed the planetary model of the atom which put all the protons in the nucleus and the electrons orbited around the nucleus like planets around the sun.
Ernest Rutherford
Most important, he postulated the nuclear structure of the atom: experiments done in his laboratory showed that when alpha particles are fired into gas atoms, a few are violently deflected, which implies a dense, positively charged central region containing most of the atomic mass.
J.J. Thomson
Therefore, he proposed a model of the atom which he likened to plum pudding. The negative electrons represented the raisins in the pudding and the dough contained the positive charge.
