Showing posts with label electron. Show all posts
Showing posts with label electron. Show all posts

April 24 – Quantum Revolution Time!!

Posted on April 24, 2018


Can you imagine a world without GPS? Without smart phones? Without the internet? Without computers?


I can actually remember the world without most of these things - and although computers were invented before I was born, the computers that existed during my childhood were so few and so so so so so so different from the computers now, I'm going to say that I remember the world without ANY of these things!

But I'm glad we have all of those things now!

All of these technologies are made possible by quantum physics (aka quantum mechanics). And quantum physics got its start on this date in 1914, when the results of an experiment were presented to the German Physical Society. Because the scientists who designed the experiment were named James Franck and Gustav Hertz, the experiment is called the Franck-Hertz experiment.




What is the key idea of quantum physics that was presented in that paper? It is that atoms have only certain energy levels that are possible for electrons. 


You might already know that atoms have a central nucleus formed by protons and neutrons, plus an outer cloud of electrons. 

One possible way for atoms to exist would be for the electrons to be just anywhere, like an informal gathering around a street performer. A lot of scientists thought this might be how atoms worked.

Another possible way for atoms to exist would be for electrons to only be allowed in certain places - and not allowed in others. This would be akin to a stadium or planetarium, where there are certain individual seats and
nobody is allowed to sit in the aisles or cluster in the front or back for safety reasons. In 1913 physicist Neils Bohr proposed this model for the atoms. And the Franck-Hertz experiment proved his model correct!

Learn more about the quantum nature of atoms in Quantum Physics for Kids.

Light and other forms of electromagnetic radiation
also have a quantum nature rather than being, as
people sorta-kinda assumed, a continuous ray
of energy. Find out more about that here.

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October 23 – Hats Off to Gilbert N. Lewis!




Posted October 23, 2016

Today we celebrate an American chemist who was nominated for the Nobel Prize in Chemistry 41 times !! – but who never won.

Obviously, with that many nominations, he added a lot to the science of chemistry!

Gilbert Lewis lived to be 70 years old – a fairly long life, to be sure – and died in his University of California, Berkeley, lab. Apparently, although the coroner ruled that he died from coronary artery disease, he was surrounded by deadly fumes from a broken line containing liquid hydrogen cyanide – and some wondered if he had actually committed suicide!

Lewis's two sons both became chemistry professors like their dad.

Here are some of Lewis's many accomplishments:

  • Figured out the electron-pair theory of acid-base reactions
  • Determined the free energies of many different substances, helping to formalize the science of chemical thermodynamics
  • Invented the concept of the covalent bond
  • Helped to create the valence theory

  • Created a system of representing valence electrons

  • Coined the term photon for the smallest “bit” of light or other radiant energy
  • First to discover O4 molecules
  • First to produce a pure sample of heavy water 
  • First to study lifeforms in heavy water
  • Contributed to the understanding of physics, including writing papers on relativity and studying the properties of the nuclei of atoms

Here are some resources to help you understand acids and bases, thermodynamics, covalent bonds and valence theory, photons, and heavy water.

And here is another resource on valence theory...



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January 3 – Rutherford's Physics Trumps Alchemy

Posted on January 3, 2015

This sculpture of Rutherford "splitting the
atom" and discovering the nucleus (although
in reality, he wore clothes as he did his
famous experiments) is found in Eastern
China, in the Qingpu Oriental Land Garden.
For centuries people had tried to create gold—precious, beautiful, heavy, shiny gold—out of “base metals.” All the greedy tinkering with materials in this attempt—experimental messing-around that went by the name alchemy—actual grew into the experimental methods of an actual science, chemistry. (Do you see the relation of the words alchemy and chemistry?)

But, it turns out, no amount of chemical tinkering can turn one element, such as lead, into another. No gold for the alchemists, no matter how hard they tried!

On this date in 1919, Ernest Rutherford did not create gold out of another element, but he did use gold foil in his experiment, and he did succeed in—for the first time ever—using science to change one element into another: 

He sent alpha particles through thin gold foil and into pure nitrogen.

And he created oxygen.

(Alpha particles are helium nuclei: two protons and two neutrons. Actually, when Rutherford sent the helium nuclei into pure nitrogen, he not only created oxygen but also leftover protons.)

This was an incredible step forward for physics, but in a way it is all of a piece with Rutherford's other accomplishments. Because of Rutherford's experiments with radioactive materials, the gold foil experiment, and later a fully controlled splitting of a nucleus, Rutherford was able to develop a model for atoms that was much more accurate than earlier models.

Um...what exactly are atoms?

Matter is largely made up of atoms. In the way olden days, people used atom to mean the smallest possible quantity of matter, which could not be further divided.

Indivisible? Then...why do we need a model? If it's indivisible, how could there be structure?

Of course, the important words in the last sentence are “in the way olden days.” Modern scientists of the early 1900s knew that there must be structure in atoms, and although they could not be divided by chemical means, Rutherford showed that natural radioactivity was in fact atoms disintegrating into smaller parts. Theoretically, humans could deliberately “split atoms.”

So what model of atomic structure did scientists come up with?

In 1904 J. J. Thomson suggested the plum pudding model of an atom.

Electrons had been discovered in 1894, and Thomson suggested that the negatively-charged electrons were scattered about in a sort of positively-charged “soup” or pudding, like raisins in plum pudding or blueberries in muffin batter.

And Rutherford disproved this model?

When Rutherford ran his gold foil experiment, he hypothesized that the alpha particles would continue through plum-pudding atoms uninfluenced by their consistent “mixture” type of structure. However, he discovered that a small portion of alpha particles were deflected, which would only make sense if the positive charge in an atom was found only in a small central area rather than throughout the entire atom.



Do we still use Rutherford's model?

Yes and no. Thanks to Rutherford and Niels Bohr, we know that protons (+ charge) and neutrons (no charge) are in a central nucleus, but our quantum physics insists that this familiar looking atomic model, which has electrons orbiting the nucleus rather like planets orbit the sun...





...is too simplistic. Instead, electrons form a “probabilistic” cloud around the dense nucleus.


But quantum physics is hard to draw or even think about. Most “structure of the atom” model-making activities go back to the simpler Rutherford-Bohr model. 

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December 18, 2011 - Particle Party!




On this date in 1856, English physicist Joseph J. Thomson was born. He ended up discovering the electron.

And on this date in 1926, American physicist Gilbert N. Lewis coined the word photon for a “particle” or bundle of light energy.





Electrons and photons are called elementary particles because (at least as far as we know) they are not made up of smaller particles. Really, really tiny things like cells are made of scads of tinier units called molecules, which are in turn made up of atoms. A human body is made up of trillions of cells, and each one of those cells is made up of quadrillions of atoms. But atoms are made of even smaller particles: protons, neutrons, and electrons. Protons and neutrons are made up of quarks held together by strong forces called gluons.

Quarks and electrons seem to be fundamental particles—not made up of smaller parts. The forces, including gluons and photons, seem to be fundamental as well.


Learn more about particle physics at The Particle Adventure.  It really isn't so VERY difficult to understand what stuff is made of, although we do have quite a few named items in the list of fundamentals: 16, to be exact. The great scientist Enrico Fermi once said, "Young man, if I could remember the names of these particles, I would have been a botanist!"

Another easy-to-understand website is Etacude. 


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