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.
I'm not questioning whether electrons exist or whether or not they have a role in chemical bonding. I'm just asking how we know the nucleis and electrons are just parts of a larger whole, aka the atom.
I feel like I must be missing something obvious, but I can't figure it out. I have the speed of an electron, and to calculate its frequency i used p = h/λ, then subbed in p =mv and λ= v/f. Giving me the equation f = mv2/h. However, I also could use E = 1/2 mv2 and E = hf to give me the equation...
Homework Statement
The total spin of an Mg atom is zero and remains zero after absorption or emission of a photon. To which states can one of the electrons in the outer shell get by absorption of a single photon: 4s, 5s, 3p, 4p, 3d, 4d?2. The attempt at a solution
I am not sure which of the...
I've been given a question to find the magnetic flux density of the Earth if an electron is orbiting near to the surface. The answer to the question makes the magnetic force equal to the centripetal force and solves for B from there.
However, I am confused to why the gravitational force has no...
I am wondering whether electrons have a net motion against an applied constant electric field in a conductor. Intuition tells me that "of course they should", but so far the math has shown me otherwise.
Here are my current thoughts:
1) I cannot rely on the obsolute Drude's model. What's more...
Homework Statement
If a system comprised only of two electrons was physically possible (such as positronium but with two electrons), what would its energy levels be and how would they relate to the energy levels of Helium?
Homework Equations
##E_{Helium} = E_{n1}+E_{n2}=-\frac{\mu Z^2...
My question comes from the heels of frustrated google searching and a half arsed attempt to pursued the search function on these forums to find my answer. So my apologies if I havnt given diligence it’s due.
My question is inspired by an episode of Space time, on PBS, regarding the one electron...
If each electron cloud repels other electrons and other atoms, then why can two or more atoms form molecules?
Is it to do with negative and positive charges?
So some materials have sub-bands of the valence band, known as heavy and light holes (they have different curvature so different effective masses, this I understand). Sources seem to give different reasons for this, either because of anistropy in the crystal or some sort of coupling effect, but...
Ambient for lack of a better term...
I'm reading "Beyond The Cosmic Landscape". Perhaps out of date, but a very understandable explanation of QED.
Am I right to deduce that the air which surrounds us is jam-packed with electrons emitting photons?
Thanks...
Homework Statement
Suppose an object has a charge of 1 C and gains #9.38 ✕ 10^18# electrons. When another object is brought in contact with the first object (after it gains the electrons), the resulting charge on the the second object is 0.9 C. What was the initial charge (in Coulombs)...
Theory explains magnetism in iron as a combined effect of magnetic moments of electrons. Now, what is confusing me is that valence electrons in iron are supposed to be free. The valence band and conduction band overlap. So, what kind of orbital and spin-ular momentum do these free electrons...
Homework Statement
Discuss the concept of the wave-particle duality for electrons and photons and include an equation which connects the wave like and particle like properties.
Homework EquationsThe Attempt at a Solution
So I am having trouble with how to word this question and generally...
Homework Statement
An oil droplet is suspended between two horizontal parallel plates with a separation of 0.4 cm. If the potential difference of 320V is applied to the plates, determine the number of electrons transferred to/from the droplet.
Given/Known Values
mdroplet = 5.2×10-6 kg
d = 0.4...
Hello people, I have 3 questions related to the mean speed of electrons in a period potential /lattice. I've read Ashcroft and Mermin's page 139 as well as the Apendix E.
From what I understood, if one applies the momentum operator on the wavefunction of a Bloch electron, one doesn't get a...
Homework Statement
a proton and an electron initially at rest ,combined to form a hydrogen atom in ground state.A single photon is emitted in this process.The wavelength of the emitted photon is
Homework Equations
E=hc/ λ
The Attempt at a Solution e
So I know when the system is formed the...
Homework Statement
I am confused if whether the collisions in a conductor is because as the electric field pushes electrons through the material, they literally bump into the orbitals of the atoms because these atoms get in the way of the electron flow, or whether these collisions happen...
So I understand in a battery that an anode (such as zinc) and a cathode (such as carbon) are separated by an electrolyte. I also understand that the electrons want to flow into the cathode, but can't get to them, so as soon as a conductor connects the two terminals, current can flow. However...
So, I'm new to electronics and I started to build some circuits with LEDs. I read up on how LEDs work and how they consist of a doped semiconductor material etc. But when I actually went to wire the LED in, it said the anode should be connected to the positive terminal of the power source. I'm...
In an old fashioned electron microscope (the type I was meant to understand at university 50 years ago), are the electrons coherent, or do we just consider an electron interfering with itself? If they are coherent, how are they made coherent?
I have just seen a video about the most powerful microscope. The best image of that microscope
represents a sheet of carbon atoms . Can we now see
electrons in these atoms or we need a more powerful
one?
https://www.physicsforums.com/insights/can-see-atom/
Homework Statement
If atoms are neutral, then how do they share electrons with each other? In the ionic bonding the metal requires very little energy do release its valence electrons, but once they are free, I don't see a force of attraction from the non metal nucleus because it is balanced...
So in my physics textbook a problem is stated. We are given an external electric field directed downwards of 150N/C. We are then told that an electron is released in the electric field and it moves upwards 520m. Finally we are asked to calculate the change in electric potential energy of the...
My textbook in elementary Q.M. stated that orbital electrons in an atom must have stationary state
wavefunctions. Was this just a simplification, the truth being maybe that their wavefunctions can be
nonstationary for a little while, but soon decay into stationary ones? I’ve seen an answer...
Homework Statement
A current of 1600A exist in a rectangular (0.4 x 16 cm) bus bar. The electrons move at an average velocity of v. If the concentration of electrons is 1029 per cubic meter, and they are uniformly distributed, what is v?
Knowns
Current (i) = 1600A = 1600 x 1018 aA
Charge per...
Hi
So we are about to learn about the octet rule. However once you get to higher shells you can have more than eight in the "shells" or orbit? But i have not been able to find a good example of how that works or happens. Does it have a specific name? I assume we are talking about say several...
In school, I was taught that the position of an electron relative to the nucleus is only an approximation. It is very likely that the electron will be close to the nucleus and where it is 'expected' to be, but it may in fact be anywhere in the universe.
Is this correct? And does this allow...
Dear all, sorry I made a new post similar to the previous post "Initial conditions..", however, a critical point was missed in the previous discussion:
The initial conditions y(0)=1 and y'(0)=0 are fine and help in solving the Schrödinger equation, however, studying free electrons, the equation...
Homework Statement
Homework EquationsThe Attempt at a Solution
[/B]
Both electrons are in 1s orbit.
For taking out the second electron, I will have to put slightly more energy than 24.6eV.
So, the energy required to remove both electrons should be slightly more than 49.2 eV.
So, I...
I have just read that Element 118, Og, has been discovered, which it would seem will allow for a nice, neat Periodic Table again, last seen when Lw (103) was added (although that should be in Group III, but whatever, it was a nice, neat table). It seems to me that once Element 121 gets...
We all think that electric current is the electrons flow without mass transfer in conductor, i.e. charged lepton flow.
But charged baryons flow can also deemed as "electric" current, e.g. ionic current.
My question is that charged baryons flow can induce magnetic field? Same amperes, then same B...
Homework Statement
As we know in NH3, N full fills its octet with three single bonds with H and a lone pair of electrons and so H. So this molecule is stable. In BF3, F full fills their octets by three single bonds with B but B is unable to fulfill its octet. It got 6 electrons by three single...
Hi
I'm recently reading something about the moller scattering in QED, and I'm feeling a bit curious about how plane waves change their spin orientations (e.g. up to down)(I mean in the scenario that one is up and one is down). In the text it seems that it's because the electrons are...
What physical attribute of the electron causes it to experience force in one direction and not the other when it moves in a magnetic field?
As a crude analogy, when wind blows in the face of a windmill, we can intuitively see why it rotates clockwise or counterclockwise. It is because of the...
So I've read that electrons traveling inside a sheet of graphene are said to travel "masslessly". I'm interpreting this as meaning "zero apparent mass" and not zero actual mass. Presumably, the graphene doesn't somehow weigh less than the sum of its constituent electrons and nuclei.
But given...
Homework Statement
Hi! So I stumbled upon this simple "plug n' play" exercise in my Physics textbook. Basically it gives you certain molecules/atoms, and tells you to measure the Electric Charge, and its Mass. Pretty simple, but I hit upon some hickups. Anyway, let's get to it:
Find the...
Can there be a stable nucleus where one has both electrons and antielectrons (either paired or unpaired) in the atomic orbitals? For example, in a ##\beta ^+## decay, could the antielectron released by captured by the atom and remain in orbit as an electron may?
Homework Statement
Predict how many electrons will most likely be gained or lost by each element:
In this case, Gallium
Homework Equations
None (that I know of)
The Attempt at a Solution
[/B]
I know that Gallium is a metal, and metals tend to lose electrons to become cations, so I will...
In a diode, we have N side, P side, and a depletion region, made of positive and negative charged sides. N side and P side of the diodes are neutral charge.
In N side there are free electrons. In the positive charged side of the depletion region, there are positively ionized atoms that "lack"...
Hi.
First, let me introduce myself:
I m from Brazil, I studied physics a few years ago and I ended up leaving the course, today I work with software development.
I would like to know if you can help me to take a doubt:
I came up with an idea that an electron could move so fast that it would...
I have a silly question.
In a simple electrical circuit, we know that the two ends of the wire are connected to different potentials of a battery through the load. Potential difference causes the current flow.
But how the wire comes to know that the other end of it, is connected to different...
Whether the increased voltage accelerates the electrons since the current of one ampere is one coulomb of charge going past a given point per second, it seems to me somehow the most logical. but I'm interested in the opinion of others on that topic.
[Moderator's note: moved to new thread and edited slightly for context.]
Hello to everybody, i just arrived at PF and I would like to know if i may set a couple of questions. First: It's possible for paired electrons to interract if one of them (or the two of them) is (are) in a black hole...
If you were sending microwaves one direction to ionize a gas, would you be able to pull or separate the atoms from these directionalized electrons? Say you had a magnetic coil with a strong e field pulling the atoms one way while the microwaves were trying to push the electrons the other way-is...
Is there any difference between the field lines you draw when one mass approached another mass and when two electrons approach one another? If there is no difference, does this mean field lines can't be used to predict the forces both particles feel?
If electrons have a magnetic moment (or behave like they have) why don't all orient North Up in a magnetic field (pointing down)? Plus, if thought as magnetic dipoles, like poles repel, therefore all should point the same direction. In a Stern-Gerlach apparattus shouldn't the magnetic moment...
In DC, we have learned that the electrons move from their position through the conductor, resulting in a current. They leave their positions on the application of a potential difference, and move or flow in the direction of higher to lower potential, thereby causing a current.
But what about...