Charlotte Quaas

The main characters in the development of the atom were: John Dalton, J.J. Thompson, Ernest Rutherford, Neils Bohr, and Schrodinger. They were all important contrubutors to the atomic structure.

John Dalton proposed the Atomic Theory in 1803 which stated that (1) all matter was composed of small indivisible particles termed atoms, (2) atoms of a given element possess unique characteristics and weight, and (3) three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules).

In 1887 J.J. Thompson discovered the first component part of the atom; the electron. In 1904 he proposed an initial model of an atom which he pictured as a sphere full of an electrically positive substance mixed with negative electrons, like chocolate chip pudding.









Ernest Rutherford discovered the atomic nucleus. His new model of the atom showed that it's positive electric charge and the majority of it's mass were concentrated in a nearly point sized nucleus. The electron in an atom circles the nucleus like the planets orbit the sun, and the attractive electron force plays the role which gravity plays with the planets. Which is where we get the name "atomic planetary model".


In order to take account for atomic stability, in 1913 Niels Bohr created a new model of the atom: "The orbits of the electron cannot be anywhere but quantified; only certain particular orbits are permitted for the electron". It's not until one jumps from one orbit to another that it can emit light.
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Erwin Schrodinger shows us that these electrons don't even move. The waves are stationary. Each time you check where an electron is you will find it in a different place, but that doesn't mean it's moving in between checks. For some energy levels, if you check position enough times you may see an "orbit-like" pattern, but don't be fooled into thinking that electrons are actually moving around in little circles.


These people were different because they had the patience and enjoyment in studying and coming up with theories about things to small for the naked eye to see. Plus these scientists all dared to be different by being smarter than all of the people of the era they lived in.

Some of these scientists grew up with a great education and rich families while others just simply had to come up with the tools they needed to perform their research the hard way; by making them or just using what they had at the time.

The atomic theory is still considered a theory because there are more discoveries made on it and many questions still unanswered. It is still being tested and changed and has no specific definition.

Understanding the atom also helps us understand the world around us since the world is made of atoms. Plus we might need to know about an atom for like a test of something important in class.