2. A Brief History of the Atom! By: Stephanie Thaler Picture from: http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/atommodels.htm

3. 34 Listen closely my students and you will hear all the fuss… that was created by the Greek philosopher Democritus. A long time ago in the city of Greece, Democritus was pondering chalk and it’s smallest piece. “I wonder” he said looking down at the floor, “If after a certain point the dust can’t be broken down anymore.” “a very small piece indeed,” thought Democritus, “I shall call this small piece atomos.” Picture from: http://darkside.hubpages.com/hub/democritus

4. 12 Many years later an additional man, whose name was John Dalton came up with a plan. He agreed that atoms where the smallest you could go, but thought things needed to be tested before they could be confirmed as so. He developed some rules that explicitly stated atoms could not be destroyed or created. Another idea he had that was fantastical Were that atoms of the same element must be identical. Picture from: http://www.chemistryland.com/CHM130S/05- EarlyAtom/EarlyAtom.html

5. 34 Because Dalton’s theories could now be tested his atomic model ended up being bested. “The atom” said Thomson, “must have two sections, which means that your model needs some minor corrections.” “Compared to these pieces the atom is large, It is made up of negative electrons embedded in a positive charge.” Picture From: http://mdkchemistry.blogspot.com/2013/01/111- rutherfords-experiment-and-atomic.html

6. 56 Soon Thomson’s ideas were left out in the cold by Rutherford and his foil of gold. “Your model,” said Rutherford, “doesn’t make sense.” “The whole inner filling is much to dense.” “My experiments are showing me this is the gist, a small dense inner sphere called the nucleus is where the positive charges exist. And instead of electrons being stuck there like glue, there is mostly empty space between the two.” “I agree to a point,” Stated Bohr with a sigh, “But your placement of electrons seems wrong, I’ll tell you why.” “If we look at your model, the one right below, We can see that the electrons have somewhere they want to go. The positive charge is pulling them in, The solution must be there is some sort of spin. But moving so much would cause the electrons to tire, A situation that I fear might be dire.” Picture from: http://www.rsc.org/chemsoc/timeline/pages/1911.html Photo from: http://c85c7a.medialib.glogster.co m/media/61/614ff53e2c77dd2dba1 0b4903e339b9008cccfd87beb0af2 d252639e0cda4cdb/rutherford- 20model.gif

7. 78 “Suppose for a second, pretend if you would, The electrons don’t lose any energy, now that would be good. What if like a planet they travel a circular path, Without losing energy, though that seems to defy math.” The world was aghast, that couldn’t be right! Scientists tried to disprove him with all their might! Once it was agreed that Bohr’s model passed the test, Chadwick stated “I might have the rest.” “Now you state right here the number of protons and electrons must be the same, Yet in your model the mass can’t be explained! The explanation you give seems a bit dubious, my conclusion must be there is something else in the nucleus. Photo from: http://www.epa.gov/radiation/understand /rutherford.html Photo from: http://www.universetoday.com/46886/boh rs-atomic-model/

8. 910 Now the model we’ve seen is mostly alright, But the idea that an electron path can be predicted isn’t quite right. The best we can do is make a prediction, Claiming with certainty would be fiction. Electron orbital uses abound, They tell us where electrons are probably found. As the number of electrons in an atom rises, The orbitals vary in shapes and sizes. We’ll be discussing the orbitals in additional chapters, I know the idea puts you in raptures. For now just remember the parts of the whole, We’ll also be discussing atoms more when we talk about a mole. Protons and neutrons exist in the center, Electrons rotate in a probable manner. Most of the atom is made up of empty space, Except for a dense spot called the nucleus in the center of the place. Photo from: http://faculty.clintoncc.suny.edu/faculty/michael.gre gory/files/bio%20101/bio%20101%20lectures/che mistry/chemistr.htm

9. The End!