Atomic Structure Flashcards
what is the plum pudding theory?
JJ Thomson used John Daltons theory that matter was made of tiny spheres ‘atoms’ that couldn’t be broken up. However Thomson found that electrons could be removed so that wasn’t correct. Thomson suggested that the atoms were spheres of positive charges with tiny negative electrons stuck in them like plums in plum pudding
what did Rutherford do?
In 1909 Rutherford and Marsden tried firing a beam of alpha particles at thin gold foil. They expected the positively charged particles to be slightly deflected by the electrons in the plum pudding model, however the particles went straight through but occasionally one came back out. They realised that the nucleus must be positive as it deflected those that hit it and also discovered that the atom was mainly empty space
what is Rutherford and Marsden’s nuclear model?
Rutherford and Marsden found that the nucleus is very small but makes u most of the mass of the of the atom, it contains protons and neutrons which overall gives it a positive charge. The rest of the atom is mostly empty space , the negative electrons go around the outside of the nucleus really fast to give the atom an overall size
