--------- #1255 - What Have We Learned about the Electron?
- This review covers the many things we have learned about the electron. It is a fundamental particle in our Universe that is responsible for electricity, electronics, chemistry, biology, and the neurological thinking that goes on in your brain. So, in a way, in reading this review your electrons are studying themselves.
- The electron and the proton form the simplest atom, the element hydrogen. It has a single positively charged proton in the nucleus and a single negatively charged electron orbiting the nucleus. The electron is 1,836 times smaller than the proton. Together in the atom they occupy a diameter of about 0.1 nanometers. Both particles are very small which means that the atom is mostly occupied by empty space, ( if space is really empty?). The proton and the electron are opposite electric charges. Opposite charges attract. So, why are the electron and protons not slamming into each other?
- The electron is orbiting the nucleus, so, maybe it is the angular momentum of the circling electron that is keeping it from falling into the nucleus? This would be similar to the angular momentum of Earth’s orbit keeping it from being pulled by gravity into the Sun. Unfortunately it is not that simple. The electron is much more complicated, we need to learn more.
- When an electron is in motion the moving electric field generates a magnetic field. When an electron is moving through a magnetic field it exerts a force (Lorentz Force) in a direction perpendicular to the plane defined by the magnetic field and the electron’s velocity. This centripetal force causes the electron to follow a helical trajectory through the field. The acceleration created by traveling in a circle induces the electron to radiate energy ( Synchrotron Radiation). An electron that is not undergoing acceleration is unable to emit or absorb a photon.
- The electron is loosing energy traveling in a circle with constant acceleration, so, why doesn’t it slow down and fall into the nucleus? The reason is the electron is a wave and the orbitals around the nucleus are standing-waves in resonance as electron waves. Energy comes in packets causing each orbital for the electron to be at a different energy level.
- The electrons in each orbital have angular momentum with a very strange property. The electron’s momentum in orbit can only exist in one of two states. The arbitrary name for the two states is “½ spin up“, and “½ spin down”. We humans have “ spin 1”. With a spin 1 we turn around 360 degrees and we are back where we started. Electrons with “ spin ½” have to turn around twice, 720 degrees, to get back to where they started. Electrons are not the only particle to have this strange ½ spin property. Protons are made up of particles called Quarks that are ½ spin. Together they make up “ordinary matter” and are called “ Fermions” , which are all particles with a spin of ½.
- Protons are made up of three Quarks, two Up-Quarks and one Down- Quark. Neutrons are the neutral charged particle in the nucleus that are made up of one Up-Quark and two Down-Quarks. Quarks are held together in the nucleus by force carrier particles called Gluons. And, electrons are held together in the atom by force carrier particle called Photons. Force Carrier particles are called Bosons and all Boson particles have a spin 1.
- Electrons, like all the Particles have an equivalent Anti-particle of opposite charge. The Anti-electron is exactly like the Electron, with all the same properties, except it has a positive charge. The anti-electron is called the “Positron”. All of the Anti-particles are the “charge reflection” of their Particles.
- One of the biggest mysteries in the Universe is why our Universe is made up of matter and the only anti-matter around is that small amount that is created in the physics laboratories, and possibly at the center of the galaxy. If the Universe started from nothing, the Big Bang would have created an equal amount of matter and anti-matter. The sum of all the particle charges would be neutral and add to zero. What can account for this imbalance of matter over anti-matter in the Universe remains a mystery.
- When electrons and anti-electrons come together they annihilate each other in a burst of Gamma Ray photons. In these collisions the mass converts back to energy according to
E = m*c^2.
- The mass of an electron is the same as the mass of an anti-electron, both are 9.1 * 10^-31 kilograms.
- The speed of light squared is 9 * 10^16 meters squared per seconds squared.
------------------- E = m * c^2
-------------------- E = 9.1 * 10^31 * 9*10^16 kilograms * m^2 / sec^2
-------------------- E = 81.9 *10^-15 joules of energy.
--------------------- 1.6 * 10^-19 joules of energy = 1 electron-volt of energy.
--------------------- E = 511,000 eV
- When the electron and the anti-electron annihilate each other the total energy released in Gamma Ray radiation is exactly 1,022,000 electron-volts. This is exactly the level of energy radiation astronomers have detected coming from the center of the Milky Way Galaxy. Somehow electrons and anti-electrons are being created and destroyed at the center of the Galaxy. This too remains a mystery.
- Energy is not continuous. At the smallest scales energy exists in tiny bundles, called Quanta. Each Quantum is the same and contains exactly Planck’s Constant of Action. Action is the physic’s term for Energy times time, ( A = E * t ). Planck’s Constant of Action = 6.626 * 10^-34 joule - seconds.
- The wavelength of an electron can be determined as the ratio of Planck’s Constant and the electron’s momentum. ( w = h / p ). Momentum is mass times velocity. The electron’s velocity in the atom is about 10% the speed of light. True calculations would require equations from the Theory of Relativity. But, let’s get the ideas using classical equations. The mass of the electron is 9.1 * 10^-31 kilograms. The velocity is 3 * 10^7 meters per second. ( p = m * v ).
----------------- The momentum of the electron is 27.3 * 10^-24 kilogram * meters / sec
----------------- The wavelength of the electron is 0.0243 nanometers.
- The diameter of the atom is 0.1 nanometers. So, the electron’s standing wave in the orbitals is much smaller then the circumference of the orbit. Classically we think of Angular Momentum and Magnetic Moments as depending on physical dimensions of an object. The electron appears to be a dimensionless object, a wave with only probabilities of position. So, how can we explain how electron’s stay in orbit around the nucleus?
- We already know the electrons can turn into photons and vise versa. Electrons and Anti-electrons turn into Gamma Rays and Gamma Rays can turn into Electron - Anti-electron pairs. So, when an electron’s charge generates an electric field , it creates “virtual photons” that continually go into and out of existence. This happens so fast it is “virtual” and not “real” but “enough real” to cause the electron to jitter. This jitter in turn causes the electron’s net circular rotation to wobble. This wobble results in a rotation of the axis called “precession“. To visualize this think of a top that is spinning and wobbling in circles as it moves across the floor. Quantum jitter in this fashion gives the electron both “ spin” and “ magnetic moment”.
- I told you the simple electron was complicated !!!!
- Each orbital in the atom contains its own quantum numbers of angular momentum, up and down spin, and energy levels. No two electrons can occupy the same quantum numbers in any orbital, ( the Pauli Exclusion Principle). Electrons can transfer between orbitals by emitting or absorbing a photon with an energy level that matches the difference in potential energy between orbitals. It is amazing that this is what creates all the colors you see around you. The photons from red to blue, from 700 nanometers to 400 nanometers wavelength, represent the photons of light at different energy levels in the atoms that you are admiring.
- When atoms form molecules the electrons in the outer orbitals are transferred, or shared with other atoms. The electrons then occupy Molecular Orbitals much the same as the Atomic Orbitals in isolated atoms.
- The even stranger property of electrons is saved for last. The electric charge of the electron generates an electric field. A moving electric charge generates a magnetic field. Somehow this electromagnetic field interconnects with everything else, all the time, and everywhere. No matter how far apart they are. Electrons seen in this way are little clouds with a foggy core and misty edges, except there are no edges. The cloudy field has infinite range, or at least to the edges of the Universe, assuming the Universe has edges. This interconnection has been experimentally demonstrated to be action-at-a-distance, faster than the speed of light. It is called “ Entanglement”. An electron with spin up can flip down and cause an entangled electron on the Moon to instantaneously flip up.
- Electrons make our muscles work and power the neurons in our brains. And, are somehow connected with the entire Universe.
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(1) #1226 “Electrons Muons, and Taus”
(2) #730 “Anti-matter”
(3) #731 “ The Electron”
(4) # 507 “ What is an Electron and the Lorentz Factor”
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RSVP, please reply with a number to rate this review: #1- learned something new. #2 - Didn’t read it. #3- very interesting. #4- Send another review #___ from the index. #5- Keep em coming. #6- I forwarded copy to some friends. #7- Don‘t send me these anymore! #8- I am forwarding you some questions? Index is available with email. Please send feedback, corrections, or recommended improvements to:
707-536-3272, Tuesday, May 17, 2011jamesdetrick@comcast.net. or, use www.facebook.com, or , www.twitter.com.
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