AND if they already knew that the electron was small and negative, then the atom must have a small positive nucleus with the electrons around them. If the positive alpha particles mostly passed through the foil, but some bounced back. How could that be if the plumb pudding model was correct? Rutherford's experiment prompted a change in the atomic model. Rutherford found that most of them went right through the foil. If you shoot these positive alpha particles at this positive pudding atom, they should mostly bounce off, right? Well, that is not what happened.
![democritus atomic theory date democritus atomic theory date](https://image1.slideserve.com/2417911/democritus-l.jpg)
He shot some alpha particles (which are really just the nucleus of a helium atom) at some really thin gold foil.
![democritus atomic theory date democritus atomic theory date](https://showme0-9071.kxcdn.com/files/579628/pictures/thumbs/1357372/last_thumb1390798663.jpg)
Atoms can differ by factors such as mass thus making Isotopes.
![democritus atomic theory date democritus atomic theory date](https://www.biochemtuition.com/wp-content/uploads/2015/09/Democritus-2.png)
Believed of extremely small particles known as “atoms”.Dalton revised Democritus’s atomic law through experimental trial.Studied gases and came up with his atomic theory.Dalton did many experiments with gases and compounds that provided evidence for the existence of atoms. Through his interests in atmospheric pressure he was led to gases Around 1800, the English chemist John Dalton reintroduced the idea of the atom, which was first introduced by the ancient Greek philosopher named Democritus.Researched color blindness which he had.Teacher at the age of twelve, principal 5 years later.Religious man, he was a Quaker, kept him from his fame.Born September 6, 1766, in Eaglesfield, England.
![democritus atomic theory date democritus atomic theory date](https://i1.wp.com/www.compoundchem.com/wp-content/uploads/2016/10/The-History-of-the-Atom-%E2%80%93-Theories-and-Models.png)
John Dalton’s Atomic Theory Ryan Templeton, Sam Sanavi One of these philosophers was Democritus (460-370 B.C.E.), often referred to as the 'laughing philosopher' because of his emphasis on cheerfulness.