The chocolate chip cookie model of the atom, also known as the plum pudding model, was developed by J.J. Thomson in 1897. In this model, Thomson proposed that the atom is a sphere of positive charge with negatively charged electrons embedded within it, similar to chocolate chips distributed throughout a cookie or raisins in plum pudding
. Thomson's model was the first to assign a specific internal structure to the atom, explaining the presence of electrons and the overall electrical neutrality of atoms by balancing negative electrons with a positive charge spread throughout the atom
. This model was later replaced by Rutherford's nuclear model after experiments showed the positive charge is concentrated in a nucleus rather than spread out
