History of the Atom

Question 1

JJ Thomson (1/3)

Answer 1

While experimenting with a cathode ray tube, he discovered that the electronic rays going through the tube were all attracted towards the positive magnet and away from the negative magnet.

Question 2

JJ Thomson (2/3)

Answer 2

He used the information from his cathode ray tube to identify a tiny particle within the atom called an electron. This disproved Dalton’s postulate stating that all atoms are indivisible.

Question 3

JJ Thomson (3/3)

Answer 3

Thomson described the arrangement of the electrons in the atom as being scattered evenly throughout the positive matter, like raisins embedded in a pudding. For this reason the model is referred to as “Thomson’s Plum Pudding Model”

Question 4

Ernest Rutherford (1/3)

Answer 4

While researching different types of radiation, he decided to test the behavior of Alpha Particles. He shot these positively charged particles at a piece of gold foil.

Question 5

Ernest Rutherford (2/3)

Answer 5

According to Thomson’s Plum Pudding Model, the positively charged Alpha Particles should have been replaced by the many positive charges scattered throughout the atom, however, he found the opposite. Most of the Alpha Particles went straight through the gold foil, only a few were deflected.

Question 6

Ernest Rutherford (3/3)

Answer 6

The experiment proved that the atom is mostly empty space, the positive nucleus is very small and located in the center of the atom, with the negative electrons spread outside the nucleus.

Question 7

James Chadwick

Answer 7

Found evidence of neutrons with a mass approximately the same as that of protons.