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Particle Physics
Relatively recent experimental results have confirmed what philosophers throughout history had theorized all along; that all matter is made up of elementary particles. Those curious about this cutting-edge field of physics known as particle physics should post their questions here, including those about fundamental particles, fundamental forces, Grand Unified Theories, and the extraordinary devices that have been or need to be engineered to research them.
3,842 Questions
Who discovered that atoms had electrons proton and neutron?
Proton was discovered by E. Rutherford in 1917.
Electron was discovered by J. J. Thompson in 1897.
Neutron was discovered by J. Chadwick in 1932.
All were of English origin.
Electrons that are held most loosely in an atom are called what?
The electrons in the valence band, this can be 1 to 8 electrons (in the s and p orbitals of the outer shell) depending on the element.
How many neutrons does carbon have?
It varies. The vast majority of carbon atoms have 6 neutrons, but there are isotopes with 7 and 8 neutrons.
In our part of the universe antimatter is plentiful short-lived long-lived non existent?
In our part of the universe, antimatter absolutely exists. We use it all the time for medical imaging. For instance, the "PET" in PET scan stands for Positron (an antimatter particle) Emission Tomography. However, it is not plentiful by any means and it is very short-lived...
What is the difference between electrons and protons?
Electrons are negatively charged particles found in the electron cloud of an atom, while protons are positively charged particles located in the nucleus. Protons are about 1,836 times more massive than electrons.
How many neutrons does iodine have?
The stable isotope of Iodine is 127 atomic weight and atomic number 53. So it has 53 protons and thus also 53 electrons (to balance the positive charge of the protons) . It has 127-53 = 74 neutrons.
Generally speaking, subatomic particles are particles smaller than an atom. There are the three basic ones that make up atoms, and you probably already know that those are protons, neutrons and electrons.
If we delve more deeply into the physics of the subatomic world, more and more particles will appear. At one point, there were literally dozens and dozens of different subatomic particles, and they created what was called a particle zoo. Since then, some newer ideas regarding the world of these tiny particles has arisen, and most of the particles in the zoo were recognized as composite particles made up of a just a few fundamental particles.
Begin learning about subatomic particles by developing an understanding of protons, neutrons and electrons. Then find out what makes them up, and move from there to the number and nature of fundamental particles.
What occurs when there is a transfer of electrons?
The transfer of electrons is the movement of electrons from one atom to another atom. The atom that loses electrons becomes a positively charged ion, and the atom that gains electrons becomes a negatively charged ion. An electrostatic bond occurs between the oppositely charged ions, and this is called an ionic bond.
An electron may move to an electron shell farther out from the nucleus.
When was the electron cloud discovered?
The electron is a fundamental subatomic particle that was identified and assigned the negative charge in 1897 by Sir John Joseph Thomson (J.J. Thomson) and his team of British physicists.
What subatomic particle is in constant motion around the nucleus?
Electrons are the subatomic particles in constant motion around the nucleus of an atom. They orbit the nucleus in energy levels or shells.
What is an inner shell electron?
These are the electrons that are not the valence electrons and are also known as core electrons.
See the Related Questions and Web Links to the left for more information about valence and core electrons.
Do particles pop in and out of existence?
Some quantum theories suggest that particles can briefly appear and disappear due to quantum fluctuations in the vacuum. This phenomenon is known as "quantum fluctuation" and has been supported by various experiments. However, it is important to note that these virtual particles cannot be directly observed and have a very short existence.
Which subatomic particle distinguishes one element from another?
The number of protons in an atom determines the identity of the element.
See these two related questions for more information:
[http://wiki.answers.com/Q/What_is_the_atomic_number_and_what_does_it_tell_you_about_the_number_of_protons_in_an_atom
What is the atomic number and what does it tell you about the number of protons in an atom?]
and
[http://wiki.answers.com/Q/How_do_you_find_the_number_of_protons_and_electrons_and_neutrons_in_an_atom
How do you find the number of protons and electrons and neutrons in an atom?]
How can insoluble particles can be removed from a hot solution?
Boil the solution. it works for salt water.
If the particles are insoluble, you don't need to boil anything... just filter the solution using filter paper. (Salt water is soluble -- it is dissolved, but an insoluble particle is a solid in the liquid).
How many quarks are in a normal water molecule?
One normal water molecule has 2 protons plus the quantity of 8 protons and 8 neutrons. That it is a total of 18 nucleons. As all nucleons have 3 valence quarks, then there are 54 quarks in 1 normal water molecule.
Proton car is Malaysia's national car manufacturing company. It produces mostly sedan models.
A proton is a type of particle known as a baryon. This means that protons are comprised of three separate, fundamental particles known as quarks. A proton is also called a subatomic particle, because it is found inside an atom, specifically within the atomic nucleus.
What is the super string theory?
String theory refers to any one of five specific theories that attempts to unify the four fundamental forces: electromagnetism, strong nuclear force, weak nuclear force, and the most difficult of them all, gravity, via oscillatory dimensional analysis. In other words, it attempts to mathematically describe the universe as if its foundation were based on strings, where the strings that are vibrating correspond to the number of observable dimensions.
The five string theories in and of themselves were all headed in the right direction, but lacked completeness. Therefore an all-encompassing "Theory Of Everything" (TOE) that attempts to unify the five string theories was proposed and is the current leading candidate for a TOE. This theory is called M-theory, and only works if the universe consists of 11 separate strings. The main problem with M-theory, as well as with all of the string theories, is observable evidence, of which there hasn't been any. This is why the search for the Higgs boson at the LHC at CERN is so important. If it's found, theoretical physicists can collectively breath a little easier because that means they are on the right track with M-theory. If it isn't found, that means they're back to square one.
A:String theory attempts to unite quantum mechanics and general relativity so we can make sense of the universe on all scales, at any place or time, large or small without breaking down.String theory does this by doing away with the idea that subatomic particles are point-like -- instead replacing that idea with tiny vibrating bits of energy, called strings.
They're so small, that if you enlarged a single atom to the size of our solar system, a string would be the size of a tree on earth. These strings are said to "vibrate" at different rates and that the "notes" (or different vibrational frequencies) give rise to the different properties of quarks and atoms.
Forgive the long explanation: this CAN'T be easily summed up.
Anytime one wants to describe our Universe in a way that can make useful predictions, one must create a "model" that simplifies the situation enough for someone to make a prediction. Thus, a flat map is a model of the surface of our planet, useful for predicting which direction to go when traveling short distances.
However, this "flat surface" model eventually fails, simply because our planet's surface is NOT flat. Thus, if you want to predict the best way to fly from New York to Paris, you MUST use a globe. It's a more complicated model, but more useful in that it covers more situations.
For standard model for particle physics is called (surprise!) the Standard Model. It combines special relativity with several quantum field theories into a self-consistent whole, and views particles as excited states of a quantum field.
This model has been proven to be unbelievably accurate in its predictions: experiments agree with theory at a level of ten significant digits. A theory this good is not going to be jettisoned without a good reason.
However, several problems with this model exist, chiefly that gravity does not (indeed, CAN not) exist within it. Combining gravity with quantum field theories has been a task that eluded the greatest minds of the last century.
String theory completely ignores the Standard Model, and (instead) models particles as vibrations on a string. Not a string that can vibrate in one dimension or even two dimensions, but in ELEVEN dimensions. The math, as you can imagine, is quite complicated. However, when you start with the M-Theory Model, you can end up with a self-consistent theory that includes both gravity AND quantum mechanics.
So why hasn't string theory replaced the Standard Model? Two reasons:
1) With the ST Model, you can not only get laws of physics just like those in our Universe, but you can get 10^500 OTHER laws of physics. It's like saying that one can predict the exact total profit of all corporations in the world (P[Total]) with the formula
(P[Total]) > 0
Yes, this formula DOES give the right answer, but it also gives a lot of OTHER answers.
2) It's not only presently impossible to develop an experiment to test whether ST is true, it's presently inconceivable. We don't just need a particle accelerator twice as big as CERN, or 100 times bigger, or a billion times bigger -- we need one bigger than the Universe!!
Scientists are presently trying to overcome these two problems, either by (1) showing that the laws of our Universe are the only ones permitted by the math or (2) developing an experiment that could resolve whether ST is a better place to start than the Standard Model, or just a mathematical oddity. We hope that future minds can resolve this.
A positron is a positively charged electron. It's an antielectron - antimatter! The positron has a charge of +1 (just the opposite of the -1 of the electron), and a spin of 1/2 as an electron does. The mass of this elementary particle is about 9.103826 x 10-31 kg. The actual charge on this particle is about +1.602 x 10-19 coulombs. We write it as β+ or e+ in nuclear equations.
It was Paul Dirac who first theorized that it may exist back in 1928, and in 1932, Carl D. Anderson discovered and named the positron. How was it done? By allowing cosmic rays to pass through a cloud chamber shielded with lead and set up in a magnetic field, the electron-positron pairs that were sometimes created could be observed. Once created, the particles moved (curved) in opposite directions within the magnetic field. Simple and clever! It should be noted that Caltech graduate student Chung-Yao Chao is credited with detecting the positron in 1930, but he was unable to explain it.
We should also note that the positron is emitted (positron emission) in beta plus decay, which is a form of radioactive decay. Pair production, the "conversion" of electromagnetic energy into a positron and an electron, is also a source of positrons. Regardless of the source, the positron will always seek to "combine" with any nearby electron with the mass of both particles being converted into electromagnetic energy (a pair of gamma rays). A more detailed description and some of the other characteristics of the positron can be found in the Wikipedia article on that subject. A link is provided below to that post and also to some Related questions that will aid in understanding this critter.
What is the electron configuration of iron II?
1s2 2s2 2p6 3s2 3p6 3d6
fe 2+: remove the electrons from the highest orbital which 4S2
What is the meaning of a neutron star?
A neutron star is the remnant of a supernova explosion. Such stars are composed almost entirely of neutrons.
A typical neutron star has a mass between 1.35 and about 2.1 solar masses, with a corresponding radius of about 12 km
A neutron star is so dense that one teaspoon (5 millilitres) of its material would have a mass over 5 trillion kg. The force of gravity is so strong that an object falling from just one meter high would take a microsecond to hit the surface but at around 2,000 kilometres per second, or 4.3 million miles per hour.
How do you count the valence electrons of an atom?
Take the atomic number then subtract the amount of valence electrons.
Example:
Number of non valence (inner) electrons in Sulfur:
16 (atomic number) - 6 (valence electrons) = 10 (valence or inner electrons)
