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picture of the greek model of the atom
Democritus pictured atoms as solid little objects that came in all different shapes. The different shapes accounted for all the different ways they could stick together to make different materials. This model was never very popular among the ancient Greeks.
Here's a link to a more detailed historical discussion: http://www.bookrags.com/biography/democritus/
(republished on 07/21/06)
Follow-Up #1: original Greek atoms
who invented the greek atom?
- rashni (age 14)
south ozone park
It's hard to know who thought of what first, but I believe that Leucippus was the first person we know about who said everything is made of atoms. Democritus was perhaps the most important advocate of this idea.
It's important to realize that the things we now call 'atoms' wouldn't have qualified for the Greek name, which means 'uncuttable'. The things we call atoms can be broken into electrons and nuclei, and the nuclei are further breakable into protons and neutrons. It's a historical accident that the name 'atom' got attached to things which were very briefly not known to be divisible.
(published on 04/05/09)
Follow-up on this answer.