Does the mass of an electron change with its "energy state"? - Physics Stack Exchange most recent 30 from physics.stackexchange.com 2019-07-17T21:19:01Z https://physics.stackexchange.com/feeds/question/149744 http://www.creativecommons.org/licenses/by-sa/3.0/rdf https://physics.stackexchange.com/q/149744 19 Does the mass of an electron change with its "energy state"? Youstay Igo https://physics.stackexchange.com/users/65672 2014-12-01T04:41:56Z 2017-11-06T07:46:57Z <p>When an electron absorbs a photon, it gets into a higher energy state and goes into the upper orbit/shell.</p> <p>Does (rather should) this absorption of energy also have an impact on its mass (although incredibly small)?</p> <p>Can we even measure the mass of an electron while it is it still bound to the nucleus?</p> https://physics.stackexchange.com/questions/149744/-/149749#149749 29 Answer by Geoffrey for Does the mass of an electron change with its "energy state"? Geoffrey https://physics.stackexchange.com/users/32185 2014-12-01T05:22:32Z 2014-12-01T05:41:35Z <p>A particle's rest mass never changes. It's mass is a natural constant, and one of the numbers which uniquely identifies it (like its spin). On the other hand, the <a href="http://en.wikipedia.org/wiki/Invariant_mass">invariant mass</a> of the atomic system does increase as the electron becomes excited, bringing the atom into a higher energy state. In that sense, the atom (not the electron) gets "heavier" because of the increased energy of the internal configuration of particles.</p> https://physics.stackexchange.com/questions/149744/-/149758#149758 -1 Answer by HolgerFiedler for Does the mass of an electron change with its "energy state"? HolgerFiedler https://physics.stackexchange.com/users/46708 2014-12-01T06:49:51Z 2014-12-01T06:49:51Z <p>Even a free electron gets heavier under the influence of accelerating photons. Best example are colliders where some amount of photons energy stay on the electron and some amount the electron looses again. Then faster the electron then higher the loose. Physics lives from models and interpretations and your interpretation is nice. It brings closer together the terms energy and mass. </p> https://physics.stackexchange.com/questions/149744/-/149763#149763 29 Answer by John Rennie for Does the mass of an electron change with its "energy state"? John Rennie https://physics.stackexchange.com/users/1325 2014-12-01T08:05:22Z 2014-12-01T08:05:22Z <p>This is really an extended comment to Geoffrey's answer, so please upvote Geoffrey's answer rather than this.</p> <p>The <a href="https://en.wikipedia.org/wiki/Isotopes_of_hydrogen#Hydrogen-1_.28protium.29">mass of a hydrogen atom</a> is $1.67353270 \times 10^{-27}$ kg. If you add the masses of a proton and electron together then they come to $1.67353272 \times 10^{-27}$ kg. The difference is about 13.6eV, which is the ionisation energy of hydrogen (though note that the experimental error in the masses isn't much less than the difference so this is only approximate).</p> <p>This shouldn't surprise you because you have to add energy (in the form of a 13.6eV photon) to dissociate a hydrogen atom into a free proton and electron, and this increases the mass in accordance with Einstein's famous equation $E = mc^2$. So this is a direct example of the sort of mass increase you describe.</p> <p>However you can't say this is an increase of mass of the electron or the proton. It's an increase in mass of the combined system. The invarient masses of the electron and proton are constants and not affected by whether they're in atoms or roaming freely. The change in mass is coming from a change in the binding energy of the system.</p> https://physics.stackexchange.com/questions/149744/-/150279#150279 0 Answer by Guill for Does the mass of an electron change with its "energy state"? Guill https://physics.stackexchange.com/users/24116 2014-12-03T19:23:03Z 2014-12-03T19:23:03Z <p>In the example you site, you are talking about a <strong>bound</strong> electron. In this case, the <strong>electron</strong> does not gain (any kind of) mass because the energy of the photon goes into <strong>changing the state</strong> of the electron (to a higher energy state). This energy is "given back" when the electron returns to its previous state, giving off an equivalent photon. </p> https://physics.stackexchange.com/questions/149744/-/367280#367280 -1 Answer by Dzidza Mawuli Yao Emmanuel for Does the mass of an electron change with its "energy state"? Dzidza Mawuli Yao Emmanuel https://physics.stackexchange.com/users/174507 2017-11-06T07:46:57Z 2017-11-06T07:46:57Z <p>I performed an experiment to take data on frequency of circular motion (f) and how it relates to the length (L) of a pendulum. In the experiment the pendulum is displaced through large angle to perform horizontal circle. Ten revolution is timed.</p> <p>From the observation it is showing that the frequency, f, is inversely proportional to the length, L, of the pendulum, but directly proportional to the velocity, v, of the circular motion.</p> <p>f--_ kV/L. Introducing f--_w/2pi and V--<em>rw f--</em> V/2pirL . From this equation frequency is inversely proportional to the radius, r,.</p> <p>This mathematics from my experiment had implications on the atom and its electrons that: 1. Electrons close to the nucleus have high kinetic energy and they move at high velocity while those that are far have high potential energy and they move at low velocity. So, kinetic energy decreases as the radius increases. 2. It confirms the uncertainty principle which focuses on the position and momentum of the electrons and its location at a given time. Electrons close to the nucleus have large momentum so uncertainty of their position is high, but those electrons that are far from the nucleus have less momentum so uncertainty of their momentum is high. This is caused by the frequency of their circular motion. 3. The observation explain why the size and mass of atoms increase down a group in the periodic table because the radius of the atoms increases while the frequency of the circular motion of the electrons decreases. 4. The observation point to the fact that the mass and size of electrons depend on their distance from the nucleus , hence electrons in the same atom have varied masses, though the difference is insignificant and are of different sizes. So, electrons have size though they may be point--like particles. I am still working on the experiment. This experiment explains some absurdities in the solar systems and its arrangement.</p> <p>My name is Dzidza Mawuli Yao Emmanuel From Ghana in West Africa. Living in Volta Region. Teaching in Some Senior High School, Agbozume--Ketu South District. E-mail: edmydzidza@gmail.com</p>