Read Aloud the Text Content

This audio was created by Woord's Text to Speech service by content creators from all around the world.

Text Content or SSML code:

400 BC Democritus - empty world proposal. 1897 through 1898- JJ Thomson credited with the discovery of the electron. Plum pudding model Of the atom. the model had negatively charged electrons evenly distributed throughout a sphere of positively charged material. Millikan discovered the charge of the electron. Ernest Rutherford discovered the proton. James Chadwick discovered the neutron. Sum of protons and neutrons is atomic mass. The nucleus is made of one or more protons and a number of neutrons. Changing protons changes the element. Isotopes have the same number of protons and a different number of neutrons. if an atom has a negative charge it has more electrons.