Which particle is j. j thomson credited with discovering

Thomson in 1897 was the first to suggest that one of the fundamental units was more than 1,000 times smaller than an atom, suggesting the subatomic particle now known as the electron. Thomson discovered this through his explorations on the properties of cathode rays.

The total number of electrons is 14

Idont know. if you want an answer you need to give us some context dude.