Answer:
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.
