## Geiger and Marsden experiment

$c=\lambda v$

Ruiting Jia 4D
Posts: 65
Joined: Fri Sep 28, 2018 12:27 am

### Geiger and Marsden experiment

Can someone explain the significance of this experiment? I understand that most of the particles passed through but I don't understand why they called the atoms "blobs of positively charged jelly" or why some bounced back.

Rhea Churi 4K
Posts: 62
Joined: Fri Sep 28, 2018 12:28 am

### Re: Geiger and Marsden experiment

Geiger and Marsden performed a series of experiments where they pointed a beam of alpha particles at a thin foil of metal and measured the scattering pattern by using a fluorescent screen. They spotted alpha particles bouncing off the metal foil in all directions, some right back at the source. They noticed only a tiny fraction of the alpha particles were deflected . Most flew straight through the foil. This suggested that those tiny spheres of positive charge were separated by empty space. Most particles passed through the empty space, while a handful struck the nuclei of the atoms and bounced right back. The "blobs" were basically the particles hitting the nuclei. This should have been impossible according to the plum pudding model; the alpha particles should have all gone straight through. They then proposed a model where the atom consisted of mostly empty space, with all its positive charge concentrated in its center in a very tiny volume, surrounded by a cloud of electrons which contributes to our model of the atom today.

Sara Lakamsani 4D
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

### Re: Geiger and Marsden experiment

So, the positively charged alpha particles were only deflected if the got close to the nucleus?

keyaluo4C
Posts: 54
Joined: Fri Sep 28, 2018 12:17 am

### Re: Geiger and Marsden experiment

Yes, some of the particles would scatter because of the nucleus making the experiments significant because it was experimental evidence that all atoms have a nucleus.