The 'plum pudding' model of the atom was proposed by JJ Thomson, who had also discovered the electron. It was put forth before the discovery of the nucleus.

In 1911, Niels Bohr earned his PhD in Denmark with a dissertation on the electron theory of metals. ... which would be expected if the atoms in the gold were like a plum pudding.

Rutherford reasoned that if Thomson's plum pudding model was correct, then when an α-particle hit a thin foil of gold, the particle should pass through with only the tiniest of deflections.

In the plum pudding model, ... This is the exact equal and opposite of the charge of an electron, which is — 1.602192 x 10^-19 coulombs. Because their charges are equal, ...

He pictured them inside an atomic ball like a plum pudding, with others later identifying their place outside the nucleus ... Electron - Wikipedia. Broadcasts. Thu 29 Sep 2022 09:00. BBC Radio 4.

Plum pudding can trace its origins back to at least the Middle Ages, when it had a less sturdy consistency. There’s a recipe in The Forme of Cury (believed to date from the late 14th century, ...