What findings led Thomson to conclude that particles smaller than the atom exists?
Thomson’s experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson’s plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged “soup.”
What evidence did JJ Thomson observe that led him to discover the electron?
In 1897, J.J. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. In addition, he also studied positively charged particles in neon gas.
What evidence first led scientists to infer that atoms have uncharged particles?
As you might expect, detecting uncharged particles is very challenging, and it was not until 1932 that James Chadwick found evidence of neutrons, uncharged, subatomic particles with a mass approximately the same as that of protons.
Why did Robert Thomson think atoms had a positive charge?
Thomson knew that atoms had an overall neutral charge. Therefore, he reasoned that there must be a source of positive charge within the atom to counterbalance the negative charge on the electrons. This led Thomson to propose that atoms could be described as negative particles floating within a soup of diffuse positive charge.
How did j.j.thomson do his cathode ray experiment?
J.J. Thomson’s cathode ray experiment was a set of three experiments that assisted in discovering electrons. He did this using a cathode ray tube or CRT. It is a vacuum sealed tube with a cathode and anode on one side.
What did the plum pudding experiment show about the atom?
Key points. Thomson’s plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged “soup.”. Rutherford’s gold foil experiment showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus.
Why was the discovery of the electron so controversial?
While controversial at first, Thomson’s discoveries were gradually accepted by scientists. Eventually, his cathode ray particles were given a more familiar name: electrons. The discovery of the electron disproved the part of Dalton’s atomic theory that assumed atoms were indivisible.