Thomson's results from experiments with cathode ray tubes produced a big change in scientific thought about atoms because <u>his results gave the first evidence that atoms were made of smaller particles.</u>
Particularly, he proved the existence of negatively charged sub-atomic particles that are called as electrons which together with a positively charged nucleus form an atomic unit.
Thomson's plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged "soup." Thomson also made the following conclusions from his experiment:
The cathode ray is composed of negatively-charged particles.
The particles must be as part of an atom because the mass of each particle is only ~ 1/2000
compared to one hydrogen atom mass.
Within the atoms of all elements, these subatomic particles are found.
Initially it was controversial, but later Thomson's discoveries were gradually accepted by scientists. After then, his cathode ray particles were given a name called as electrons.
When Lead-207 is bombarded with neutrons, the atom acquires the neutron. Adding a neutron only changes the mass number of the atom. This does not involve change in the identity of the atom. So, Lead-207 can change into Lead-208 without change in its chemical properties.
