The electron is a subatomic particle, symbol e− or β−, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry and thermal conductivity, and they also participate in gravitational, electromagnetic and weak interactions. Since an electron has charge, it has a surrounding electric field, and if that electron is moving relative to an observer, said observer will observe it to generate a magnetic field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law. Electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields. Special telescopes can detect electron plasma in outer space. Electrons are involved in many applications such as tribology or frictional charging, electrolysis, electrochemistry, battery technologies, electronics, welding, cathode ray tubes, photoelectricity, photovoltaic solar panels, electron microscopes, radiation therapy, lasers, gaseous ionization detectors and particle accelerators.
Interactions involving electrons with other subatomic particles are of interest in fields such as chemistry and nuclear physics. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms. Ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge 'electron' in 1891, and J. J. Thomson and his team of British physicists identified it as a particle in 1897 during the cathode ray tube experiment. Electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. The antiparticle of the electron is called the positron; it is identical to the electron except that it carries electrical charge of the opposite sign. When an electron collides with a positron, both particles can be annihilated, producing gamma ray photons.
In a covalent bonded molecule, what is the force responsible for the molecule staying together. To my knowledge it's to do with electrons of opposite spins and being at a lower energy with valence shells filled but what is the force itself that pulls a second atom along if the atom it's bonded...
Just a quick question. We know that an accelerated electron shoots out light, and light that falls on an electron in an atom, excites it. But what happens to an electron in vaccum, when it encounters a laser beam?
If an electron beam from an electron microscope, were to to intercept a laser...
Question in my textbook:-
The wavelength of light from the spectral emmision line of sodium is 589 nm.
Find the kinetic energies of electron and neutron at which they both have same de broglie wavelength.
Logically, since light of same energy is falling on both then their kinetic energies must...
Moved this question from the quantum physics section to this section, since... Well it fits this section better since electrons apparently do obey conservation of momentum in the 'classical' sense.
Why not produce thrust in microgravity with electrons? Plenty of harnessable electricity in...
Electrons have a theoretical rest mass. They can move at varying speeds through space, unlike photons. They ehxhibit quantum-characteristics in their behavior. If an electron collides with, say, an atom, does conservation of momentum apply in the classical sense or does measurable mass (an atom...
The charge of an electron is -e in energy scales well into the atomic scale. At infinitesimal scales it becomes infinite. This relation must be continuous for re-normalization to work, thus the intermediate value theorem asserts that it attains all values between at some energy level. I want to...
i am just a student who wishes to learn more about physics and the way the universe works, but because i am 14 and am just starting to learn all of this on my own i have to start from scratch, please present me with any usable information
I was trying to determine the bandgap in the nearly free electron model. I'm having trouble to determine the band gap bewteen the second and the third band. Its a one dimensional problem.
So, the central equation reads:
##\displaystyle \left [ \frac{\hbar}{2m} (k-G)^2-E \right ]c_{k-G}+...
Homework Statement
My book is saying that if a nucleus has too many neutrons beta minus decay or electron capture is going to happen. The nucleus wants to get rid of a neutron so it is going to send out one electron and an antineutrino that originally comes from the neutron. But what I don't...
Homework Statement
Photon of energy E=0,3MeV is scattering at an angle \phi=\frac{2\pi}{3}. Calculate the energy E' of scattered photon and emitted electron.
Homework Equations
-Compton effect
The Attempt at a Solution
By Compton effect...
Hi All,
Having difficultly figuring out where I've gone wrong with this problem. Any guidance gratefully received.
1. Homework Statement
A 4.76 keV electron (an electron that has a kinetic energy equal to 4.76 keV) moves in a circular orbit that is perpendicular to a magnetic field of 0.392...
Homework Statement
Hi!
I really need help with finding time- dependent continuity equation for electron densities in the atmosphere. I've tried to solve it without any success. My question is if someone can give me a good link/link or equations that I can start with.
Homework Equations
See...
Homework Statement
Calculate the wavelength of an electron which has 5eV of energy.Homework Equations
de Broglie's equation: lambda=h/p , kinetic energy equation: K=0.5mv^2
The Attempt at a Solution
My attempt: I figured out that using de Broglie's wavelength equation was necessary for this...
In the CODATA table of physical constants, there are very precise numbers given for mass of electron and mass of proton. And an even more precise number for proton electron mass ratio. But when you divide the mass of proton by the mass of electron, you don't get the same number as the proton...
For example, a cosmic electron projectile at 1TeV, is it possible to fly through a nucleus just like a bullet drills through a cake and makes the cake insensible recoil?
After drill-trough, the electron may have some deviation from incident direction because the route may not exactly pass the...
Homework Statement
To what velocity would an electron (neutron) have to be slowed down, if its wavelength
is to be I meter? Are matter waves of macroscopic dimensions a real possibility?
2. Homework Equations
I have assumed this could apply to pretty much any free particle of mass m, and is...
If you raise the electron to other higher shell states, can light transmission throug
-h a SOLID BLACK opaque object.
Modified the original question because it was unclear.
I won't repeat the same question over, and over, but what I have said in previous questions may get repeated in the...
Okay guys
Felt a need to post this since it's been confusing me for a long time
Say,for example,we have an atom with its electron occupying the 3s orbital
Now let's say we energise the atom and constantly supply it energy that the electron which receives the energy(or a part of it)gets excited...
I was studying for (first year) physics class and was playing around with the Bohr Model of Hydrogen. I tried calculating the electric potential at the Bohr radius r =5.29e-11 m, where V = \frac{e}{4 \pi \epsilon_0 r} (from the point-charge formula for electric potential) and I got 27.19 J/C...
I was reading an interview of Dr Subir Sachdev in the latest online issue of Quanta Magazine, and he mentions that Cooper pair electrons in the high temp superconductors (HTSC's) are globally entangled with one another, but in the low temperature (type 1) superconductors, they are not, and I...
Homework Statement
Let’s introduce an imaginary atom which can replace the silicon atom and
generate one mobile electron. What is electron density when all silicon atoms are replaced by this imaginary
atom
Homework EquationsThe Attempt at a Solution
I have tried looking for a formula to...
Hello PF members,
In Newtonian perspective, applying a force to a object like ball causes it starts to moving and getting more speed and more energy.
Do photon apply a force to the electron when it interacts with the atom and electron absorbs it?
It seems electron gets more energy and goes to...
Homework Statement
Consider an electron with spin ##\vec{S}## and magnetic moment ##\vec{\mu}=-\frac{e}{m}\vec{S}##. It is moving with the velocity ##\vec{v}(t)## relative to the inertial frame of reference ##I## through the electric field ##\vec{E}##. Calculate the angular momentum the...
Homework Statement
2 parallel plates of length 4.0 cm are arranged horizontally in a vacuum. The upper plate is positively charged and the lower plate is negatively charged. An electron is projected horizontally with an initial velocity of 6.0 x 106 ms-1 and experiences a constant electric...
Hi all, I'm new to the forum so I hope this is the right place to pose this question. I've managed to find answers to nearly all of the questions I've had regarding certain aspects of physics on the forums, but haven't seen this addressed anywhere.
According to Wikipedia (...
Homework Statement
A conduction electron moves through a block of Cu until it reaches the surface. At the surface the electron feels a strong force exerted by the nonuniform charge distribution in that region. This force tends to attract the electron back into the metal which is what causes the...
I am trying to understand selection rules in atomic transitions.
So, one of the selection rules says that only transitions where orbital quantum number is changed by 1 are possible. If that is the case how can hydrogen in ground state get to 2s state? Can we detect spectroscopic line that...
The book I'm reading is discussing the physics of semiconductors. I'm having a hard time understanding a passage in section introducing n-type semiconductors.
(Phosphorus is used as the impurity)
The book says:
"At normal operating temperatures, this extra electron breaks its bond with the...
Homework Statement
The motion of an electron is given by x(t)=pt^3 +qt^2 +r, with p = -1.9 m/s^3 , q = +1.3 m/s^2 , and r = +9.0 m.
What is the velocity at: a) t=0s b) t=1s c) t=2s d t=3s
Homework Equations
v=x/t
The Attempt at a Solution
I have tried plugging in the time to equal to t, in...
Does anybody happen to know the strength of the electroMAGNETic lenses of a scanning electron microscope?
I was thinking of using solenoid coils, which would be enough if I am willing to increase the focal distance, but the lenses on SEM's seem far larger.
I would like to calculate the electron kinetic energy ejected from a cathode as a function of the electric field and pressure without known of the temperature and velocity.
Hi,
I am a newby so please excuse my ignorance.
With reference to the single electron double slit experiment, one thing has been bugging me. The videos that illustrate the particle or wave behaviour do not tell us how the single fired electrons are directed to either the left or right slit...
Dear PF Forum,
I think I have asked too many question for one day.
I'm trying to understand antioxidant and free radicals. But, first I'd like to understand oxidation number.
The oxidation number for hydrogen is +1 or -1. I can understand that. Either Hydrogen must lost one electron or gains one...
Since the binding energy of an electron in outer shell is smaller than the binding energy of the electron in inner shell, why the photon kick out the electron orbiting in inner shell? It is always easier to kick out the electron with less binding energy, is it not?
During Internal conversion, the nucleus transfer some energy to an electron in K-shell cause the electron eject out of the atom. After which there left a hole in K-shell then either by releases auger electron or characteristic X-ray the atom de-excited itself.
During Electron capture, a proton...
Are axis of rotation and revolution of an electron revolving a nucleus parallel? if axis of rotation and revolution of Earth can be not parallel to each other then why not for electron? We add or subtract (s) = 1/2 (value of spin quantum number) to orbital quantum number (l) to get total angular...
Why is the electronegativity of fluorine higher than chlorine but not electron affinity? How is it possible that it has a stronger attraction towards a bonding pair of electrons than when a new electron is added to the atom?
Hello
Lastly I was thinking a lot about electron density definition. It is not intuitive for me and I'm looking for any mathematical tool that could explain it to me more. My friend told me about idea to derivate it from propability density function using Dirac delta distribution. I'd like to...
Dear PF Forum,
I'm interested in the future. How mankind will benefit from fusion power. But there are some terms that I don't understand.
Electron Volt.
https://en.wikipedia.org/wiki/Electronvolt
Volt
https://en.wikipedia.org/wiki/Volt
Perhaps this yes/no question will confirm my confusion...
I cannot find a website that answers this question, and all diagrams I see do not show that ATP is used. Does this mean that these processes are intrinsically spontaneous? I can see how the electron transport chain is spontaneous, as the oxidation of oxygen to water is favorable (E 1/2=0.7V).
I get the notion that an elementary particle derives from a localized perturbation of that particles quantum field. What I don't get is how that perturbation can lead to two alternative quantum states for that particle - for example, an electron with two spin states (spin up and spin down). Are...
Hi
I'd like to ask you about interpretation of electron density definition. According to the "Handbook of Molecular Physics and Quantum Chemistry" it goes like:
##\rho (\textbf{r})=N \sum_{\sigma_1}^{\sigma_N} \idotsint_{\mathbb{R^3}} |\psi_V (\textbf{r}_1, \sigma_1;\dots...
I have heard that Feynman and Wheeler briefly discussed the idea of the 'one electron universe'. According to Wikipedia it came up as follows:
It wasn't really a serious idea, more a 'thought experiment'. But what interests me is the fact that electrons are literally indistinguishable. Not...
We were digging through some of the apparatus today and amongst a few dual beam tubes we found this, pictured below
It's very similar looking to a dual beam tube shape-wise but as you can see the internal structure is quite different. What is this? After looking at it for a while we suspect...
Homework Statement
Electron on n=6 level emits wavelength of 410.2nm.
What energy level does it move too?
Homework Equations
1/L = R ( 1/N^2 - 1/n^2)
where N is initial and n final
R=1.096779*10^7 m
The Attempt at a Solution
1/410.2 = 10967790 (1/36 - 1/n^2)
1/4498975152 = (1/36 - 1/n^2)...
I was reading the book "Electricity and Magnetism" 3rd edition (Purcell, Morin) and under section 1.3 the book says (I quote):
"What holds the electron together is as mysterious as what fixes the precise value of its charge. Something more than electrical forces must be involved, for the...