Sunday, December 11, 2011
Saturday, December 10, 2011
Aristotle Messes Up Science for 2000 Years
*For more on the Humors throughout time leading up to modern medicine, this blog provides a good summary, and wikipedia's article isn't bad.
Saturday, November 26, 2011
Atomic Models
It's time for a break from comics... and time for
ATOMIC MODELS!
*in progress*
*in progress*
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| But they're all wrong. This is the real atom. |
We've learned about the Greek creation and then destruction of the idea of the atom. We know it took 2,000 to get back to this idea of an 'atom'....
And it's all thanks to a guy who couldn't even tell the difference between red and green.
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| Hint: The condition of red/green colorblindness is AKA "Daltonism". |
John Dalton was a man of many interests. He discovered the law of partial pressures because he was interested in gases because of his interest in meteorology.
His most famous contribution to the world is his atomic theory. He claimed that elements were made up of atoms, which combined to form compounds. Atoms combine in whole-number ratios (sound familiar?) and cannot be split into smaller pieces, created, or destroyed. Dalton, though he was not able to make accurate measurements, also thought that the atoms of a particular element all had the same mass. His atomic theory has held up for over 200 years, only being modified when isotopes were discovered.
Though he did not present an atomic model, Dalton laid the groundwork for those to come who had the technology to. Representing the atom visually, with a symbol for each element, is by no means a periodic table. However, it is much closer to the modern day notation than what was seen in previous writings, such as Lavoisier's Elementary Treatise of Chemistry.
His most famous contribution to the world is his atomic theory. He claimed that elements were made up of atoms, which combined to form compounds. Atoms combine in whole-number ratios (sound familiar?) and cannot be split into smaller pieces, created, or destroyed. Dalton, though he was not able to make accurate measurements, also thought that the atoms of a particular element all had the same mass. His atomic theory has held up for over 200 years, only being modified when isotopes were discovered.
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| His book, A New System of Chemical Philosophy*, was published in 1808. It had pictures. |
Though he did not present an atomic model, Dalton laid the groundwork for those to come who had the technology to. Representing the atom visually, with a symbol for each element, is by no means a periodic table. However, it is much closer to the modern day notation than what was seen in previous writings, such as Lavoisier's Elementary Treatise of Chemistry.
Skip forward a few decades, and we see the first Atomic Model.
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| Plum Pudding. Yum ....? |
J.J. Thompson proposed that atoms were positively charged spheres, with electrons throughout that made their charge neutral. He compared the atom to plum pudding- hence the name plum pudding model. I prefer to think of the model in more appetizing terms: a ball of cookie dough with chocolate chips throughout.
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| Or, in terms of an atom. |
Ernest Rutherford is our next scientist of interest.
He used α (alpha) particles are unstable, positively charged groups of two protons and two neutrons. They resemble a Helium Nucleus (and can be written as He+2), but aren't just formed by a Helium atom losing two electrons.
Rutherford is credited with the discovery of these particles when he was working with radioactive elements in 1899. He found that alpha particles were being emitted.
Because they interacted well with matter, he asked his assistants to shoot a bunch of these particles at a thin sheet of gold.
More or less, they all went right through.
He used α (alpha) particles are unstable, positively charged groups of two protons and two neutrons. They resemble a Helium Nucleus (and can be written as He+2), but aren't just formed by a Helium atom losing two electrons.
Rutherford is credited with the discovery of these particles when he was working with radioactive elements in 1899. He found that alpha particles were being emitted.
Because they interacted well with matter, he asked his assistants to shoot a bunch of these particles at a thin sheet of gold.
More or less, they all went right through.
 |
| Where's the cookie dough??! |
It turned out the positive particles were clumped together in the center- a really small center, as a matter of fact. Most of the alpha particles passed through the gold foil, only a couple were deflected off the center of the atom.
Thus, with Rutherford's experiment in 1909, another new atomic model was born.
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| The thought process that lead to the "solar system" atomic model. |
This looks like our familiar friend, happy atom!
Except with a much smaller nucleus.
To put into perspective how small the nucleus is within the diameter of the atom, we'll use the hydrogen atom, which only has an atomic number of 1. If the nucleus was the the size of a soccer ball, the electron would be 32km, or 20 miles away.
With larger atoms, the electrons are further away.
If earth, which is 7,926.41 miles from one side to the other, was an atom, the nucleus would only be the size of a football stadium.
From here, the atom becomes harder and harder to represent in a clean model.
In 1899, Max Planck, the German scientist best known as the founder of quantum physics, did important work alongside Albert Einstein. Using black body radiation, he theorized that atoms absorbed and emitted "quanta", or photons. Or energy.
Except with a much smaller nucleus.
To put into perspective how small the nucleus is within the diameter of the atom, we'll use the hydrogen atom, which only has an atomic number of 1. If the nucleus was the the size of a soccer ball, the electron would be 32km, or 20 miles away.
With larger atoms, the electrons are further away.
If earth, which is 7,926.41 miles from one side to the other, was an atom, the nucleus would only be the size of a football stadium.
From here, the atom becomes harder and harder to represent in a clean model.
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| "Ohh, you bet!" -Mr. Quantum Physics (Planck) |
In 1899, Max Planck, the German scientist best known as the founder of quantum physics, did important work alongside Albert Einstein. Using black body radiation, he theorized that atoms absorbed and emitted "quanta", or photons. Or energy.
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| It has a bit to do with waves and stuff. |
This leads into a whole lot more research with subatomic particles, which is very complex and theoretical. Quantum Physics, also known as Quantum Mechanics and Quantum Theory, was created to solve several important questions.
Are Electrons waves or particles? (Answer: both)
Why don't electrons get pulled into the positively charged nucleus? (Answer: Subatomic forces)
Is Schrödinger 's Cat dead or alive? (Answer: ... )
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| Let's hope it's dead. |
Also really important in this all are Bohr and Heisenberg.
Sources
http://wps.prenhall.com/wps/media/objects/602/616516/Chapter_02.html
*A New History of Chemical Philosophy is available for free on google eBooks.
http://en.wikipedia.org/wiki/Quantum_mechanics
http://library.thinkquest.org/3487/qp.html
http://www.brusselsjournal.com/node/2599 (Cat image)
http://www.allaboutcircuits.com/vol_3/chpt_2/2.html Rutherford Atom
Size comparison
*A New History of Chemical Philosophy is available for free on google eBooks.
http://en.wikipedia.org/wiki/Quantum_mechanics
http://library.thinkquest.org/3487/qp.html
http://www.brusselsjournal.com/node/2599 (Cat image)
http://www.allaboutcircuits.com/vol_3/chpt_2/2.html Rutherford Atom
Size comparison
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