Identify the scientist associated with each major contribution to the development of atomic theory. He discovered the electron. He discovered periodic changes in properties of elements when they are listed in order of their atomic weights. He experimented with the deflection of cathode rays by a magnetic field. He carried out experiments, using gold foil, that measured the scattering of positively charged alpha particles by heavy atoms. He proposed that atoms are the basic units of matter. He proposed the model of the atom had most of its mass concentrated in a very small nucleus. He proposed that in a chemical reaction, atoms are neither created nor destroyed. Answer Bank

He discovered the electron- J.J Thompson

He discovered periodic changes in properties of elements when they are listed in order of their atomic weights- Dimitri Mendeleev

He experimented with the deflection of cathode rays by a magnetic field- J.J Thompson

He carried out experiments, using gold foil, that measured the scattering of positively charged alpha particles by heavy atoms- Ernest Rutherford

He proposed that atoms are the basic units of matter- John Dalton

He proposed the model of the atom had most of its mass concentrated in a very small nucleus- Ernest Rutherford

He proposed that in a chemical reaction, atoms are neither created nor destroyed-John Dalton

Explanation:

J.J Thompson was the discoverer of the electrons. He also worked hard to show that they were negatively charged particles after he experimented with them using a magnetic field. He named them cathode rays.

Dimitri Mendeleev  found that, when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements(Encyclopedia Britannica).

Ernest Rutherford demonstrated by experiment using a thin gold foil and alpha particles that the atoms are composed of a positive massive core called the nucleus.

John Dalton proposed that matter is composed of atoms. Also, in a chemical reaction, atoms are neither created nor destroyed.