Plum pudding model

Thomson subsequently proposed the plum pudding model, published in 1904: the atom was a ball of positive charge with negative electrons embedded throughout it. The positive charge was spread out rather than concentrated, and the model contained no nucleus.

Thomson proposed the plum pudding model: electrons were embedded throughout a sphere of positive charge. The positive and negative charges balanced, making the atom neutral. This model had no nucleus.

Because an atom has no overall electric charge, Thomson proposed that its negative electrons were embedded in a sphere of positive charge, balancing them. This became known as the plum pudding model. It had no central nucleus: the positive charge was spread throughout the atom.

Because atoms contain negatively charged electrons but are neutral overall, Thomson reasoned that they must also contain positive charge. His plum pudding model pictured the atom as a sphere of spread-out positive matter with electrons embedded through it, rather like dried fruit in a pudding.