Particle Physics

In the periodic table, atomic numbers are given alongside the symbol of each atom. As atomic number is always equal to number of protons, so the Periodic Table also tells us about the number of protons in different atoms...

neutrons, protons and electrons.

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The above is incorrect; those are atomic particles. Subatomic particles are what those particles are made of. Quarks and leptons are subatomic particles.

Long-hand version: 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 Short-hand version: [Ar] 4s^2 Note: The "^" symbol means the the following number is in the form of a superscript.

The eV (Electron Volt) is a unit both of mass and energy. It is used as a mass unit in particle physics, for the most part. Generally, you will hear it as a unit of energy. One eV is equal to the energy gained by one single unbound electron passing through an electrostatic potential difference of one volt. But what does this mean? To most people, measureing in eV, or even TeV (Tera electron volts = trillion electron volts) is completely impractical. You walking across the floor has trillions of trillions of electron volts, or maybe even more. This measurement is only used for very small things, hence the electron! To sum it up, th eV is a measurement of the energy that an electron has.

Electrons are basically surrounding the nucleus (containing the protons and the neutrons), and are "swirling" around the nucleus, forming a cloud like shape around the nucleus.

Subatomic particles with no charges are neutrons

The three subatomic particles are:

Neutrons

Protons

Electrons.

The protons and neutrons are found in the nucleus of the atoms. The electrons are found in s, p, d and f orbitals of the energy levels which surround the nucleus.

Neutrinos are elementary particles that travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed and are thus extremely difficult to detect. Neutrinos have a minuscule, but non-zero, mass that was too small to be measured as of 2007.

The atom is composed of a nucleus surrounded by electrons (negative charge)rotating in orbits around the nucleus. The nucleus is composed of protons (positive charge) and neutrons (neutral charge). so the three main subatomic particles are: * Electrons in orbits around the nucleus of the atom * Protons (positively charged particles) in the nucleus * neutrons (neutrally charged particles) in the nucleus. Except for hydrogen that is having no neutrons.

A Neutron weighs more than a proton. Than an electron.

A Neutron weighs the most, and an electron weighs the least. A proton is in the middle. Although there are these three sub atomic particles, an atom is made up of 99 percent empty space! But from greatest to least in mass, it goes neutron, proton, then electron!

Yes. Neutrons can change through radiation. The number of neutrons determines the isotope of the atom.

The sub atomic particles to an atom are the proton (p), neutron (n). The p and n both contribute to atomic mass. The positive charge comes from the p and outside the atom in orbit is/are the electron with negligible mass, but negative charge.

Yes. The atom only bonds spontaneously if its to become more stable. So depending on the valence electrons, they have different forms of getting that stability. Let's see:

Elements from the first and second group have 1 and 2 electrons of valence, respectively, so they tend to give them up. That's why they tend to bond with ionic bonds. They never steal electrons from others.

Elements from the 17th group, are missing one electron to have their valence orbitals full, so again, they tend to steal electrons from those of group 1, forming stable ionic bonds. They can also give up some of their electrons, but more commonly they prefer to steal one.

Elements like N and C, have their valence orbitals close to 50% filled, so they tend to prefer sharing electrons, that is, covalent bonds.

Finally noble gases, have their valence orbitals filled with electrons, so they don't react with anything, and the only bonds they make, are weak Van der Waal bonds between themselves.

In a "lone pair" of electrons, the electrons are both negative charges and don't like each other. They will repel each other and get away from each other. Bonded electrons can be held closer together by the atoms involved in bonding.

A positron is a fundamental particle because it does not consist of smaller particles, which would make it a composite particle. Fundamental particles can still decay or change identity however, but they have no (at least at this point) discernible internal structure.

A proton on the other hand is a composite particle; it has an internal structure and consists of a mixture of gluons and quarks (which both are fundamental particles).

First of all refer to stability belt. Secondly take your element and calculate number of neutrons.

Now if number of neutrons lies on the stability belt then given element is stable. If it lies below stability below and is < than 84, element will decay electrons form the nucleus.

This is also known as Beta emission.

•The lowest portion of the building structure.Usually located below the ground level.

•A foundation is a part of the structure which is in direct contact with the ground to which the loads are transmitted.

As of this writing, no, it is not. Maybe spring of 2009. At least that's the word on the street. Protons were successfully circulated just recently, but there is a problem with a couple of the bending magnets which are used to accelerate and guide the beam around the curves in the plumbing. A shutdown was scheduled for the winter anyway, and now they'll add the problem of "fixing" the magnets to their "to-do list" of over-winter activities. You'll find a link to the Wikipedia post on the LHC below.

Since Nuclear radiation is simply electromagnetic waves and all electromagnetic waves travel at the speed of light all nuclear radiation travels at the speed of light. But the frequency will vary.

There are 35 protons in copper-64 (64Cu). Copper has 29 protons.

Copper-64 is not a natural isotope. It is a radioactive isotope that can be created artificially, with a half-life of about 12.7 hours.

the charge is when u hook at a tree to a mouse and it will charge

It would be better to say that neutrons do participate in the binding force that holds nuclei together, but do not alone act as the glue. Both protons and neutrons are attracted and bound in nuclei by the nuclear force. The strong force itself, a fundamental force in physics behind this short-distance attraction between nucleons, is actually mediated by another particle - the gluon.

A method of describing how many electrons are in the highest energy level in an electron. It is done by writing an element's symbol (i.e. for Hydrogen, H; and for Neon, Ne) and then placing dots around the symbol in a counter-clockwise manner. The maximum dots there can ever be is 8 (there are theorems that prove it, I believe the Aufbau Principle is the one). Their are several teachings in which the order the dots should be drawn. However, there is a consensus that up to two dots may be placed on any side of the symbol (2 on the right, 2 on top, 2 on the left, and 2 on bottom).

density is the word used to describe how much is in a certain place e.g. 100ml of salt water has a higher density than the same amount of pure H2O because the salt water has both H2O and NaCl (salt) squashed into the same amount of space therefore everything has density if however if you meant mass or weight the answer would also be yes

The nuclear binding force

As early as 1920, when Ernest Rutherford named the proton and accepted it as a fundamental particle, it was clear that the electromagnetic force was not the only force at work within the atom. Something stronger had to be responsible for binding the positively charged protons together and thereby overcoming their natural electrical repulsion. The discovery in 1932 of the neutron showed that there are (at least) two kinds of particles subject to the same force. Later in the same year, Werner Heisenberg in Germany made one of the first attempts to develop a quantum field theory that was analogous to QED but appropriate to the nuclear binding force.

According to quantum field theory, particles can be held together by a "charge-exchange" force, which is carried by charged intermediary particles. Heisenberg's application of this theory gave birth to the idea that the proton and neutron were charged and neutral versions of the same particle-an idea that seemed to be supported by the fact that the two particles have almost equal masses. Heisenberg proposed that a proton, for example, could emit a positively charged particle that was then absorbed by a neutron; the proton thus became a neutron, and vice versa. The nucleus was no longer viewed as a collection of two kinds of immutable billiard balls but rather as a continuously changing collection of protons and neutrons that were bound together by the exchange particles flitting between them.

Heisenberg believed that the exchange particle involved was an electron (he did not have many particles from which to choose). This electron had to have some rather odd characteristics, however, such as no spin and no magnetic moment, and this made Heisenberg's theory ultimately unacceptable. Quantum field theory did not seem applicable to the nuclear binding force. Then in 1935 a Japanese theorist, Yukawa Hideki, took a bold step: he invented a new particle as the carrier of the nuclear binding force.

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Hideki Yukawa.

Keystone/Hulton Archive/Getty Images

The size of a nucleus shows that the binding force must be short-ranged, confining protons and neutrons within distances of about 10−14 metre. Yukawa argued that, to give this limited range, the force must involve the exchange of particles with mass, unlike the massless photons of QED. According to the uncertainty principle, exchanging a particle with mass sets a limit on the time allowed for the exchange and therefore restricts the range of the resulting force. Yukawa calculated a mass of about 200 times the electron's mass, or 100 MeV, for the new intermediary. Because the predicted mass of the new particle was between those of the electron and the proton, the particle was named the mesotron, later shortened to meson.

Yukawa's work was little known outside Japan until 1937, when Carl Anderson and his colleague Seth Neddermeyer announced that, five years after Anderson's discovery of the positron, they had found a second new particle in cosmic radiation. The new particle seemed to have exactly the mass Yukawa had prescribed and thus was seen as confirmation of Yukawa's theory by the Americans J. Robert Oppenheimer and Robert Serber, who made Yukawa's work more widely known in the West.

In the following years, however, it became clear that there were difficulties in reconciling the properties expected for Yukawa's intermediary particle with those of the new cosmic-ray particle. In particular, as a group of Italian physicists succeeded in demonstrating (while hiding from the occupying German forces during World War II), the cosmic-ray particles penetrate matter far too easily to be related to the nuclear binding force. To resolve this apparent paradox, theorists both in Japan and in the United States had begun to think that there might be two mesons. The two-meson theory proposed that Yukawa's nuclear meson decays into the penetrating meson observed in the cosmic rays.

In 1947 scientists at Bristol University in England found the first experimental evidence of two mesons in cosmic rays high on the Pic du Midi in France. Using detectors equipped with special photographic emulsion that can record the tracks of charged particles, the physicists at Bristol found the decay of a heavier meson into a lighter one. They called the heavier particle π (or pi), and it has since become known as the pi-meson, or pion. The lighter particle was dubbed μ (or mu) and is now known simply as the muon. (According to the modern definition of a meson as a particle consisting of a quark bound with an antiquark, the muon is not actually a meson. It is classified as a lepton-a relation of the electron.)

Studies of pions produced in cosmic radiation and in the first particle accelerators showed that the pion behaves precisely as expected for Yukawa's particle. Moreover, experiments confirmed that positive, negative, and neutral varieties of pions exist, as predicted by Nicholas Kemmer in England in 1938. Kemmer regarded the nuclear binding force as symmetrical with respect to the charge of the particles involved. He proposed that the nuclear force between protons and protons or between neutrons and neutrons is the same as the one between protons and neutrons. This symmetry required the existence of a neutral intermediary that did not figure in Yukawa's original theory. It also established the concept of a new "internal" property of subatomic particles-isospin.

Kemmer's work followed to some extent the trail Heisenberg had begun in 1932. Close similarities between nuclei containing the same total number of protons and neutrons, but in different combinations, suggest that protons can be exchanged for neutrons and vice versa without altering the net effect of the nuclear binding force. In other words, the force recognizes no difference between protons and neutrons; it is symmetrical under the interchange of protons and neutrons, rather as a square is symmetrical under rotations through 90°, 180°, and so on.

To introduce this symmetry into the theory of the nuclear force, it proved useful to adopt the mathematics describing the spin of particles. In this respect the proton and neutron are seen as different states of a single basic nucleon. These states are differentiated by an internal property that can have two values, +1/2 and −1/2, in analogy with the spin of a particle such as the electron. This new property is called isotopic spin, or isospin for short, and the nuclear binding force is said to exhibit isospin symmetry.

Symmetries are important in physics because they simplify the theories needed to describe a range of observations. For example, as far as physicists can tell, all physical laws exhibit translational symmetry. This means that the results of an experiment performed at one location in space and time can be used to predict correctly the outcome of the same experiment in another part of space and time. This symmetry is reflected in the conservation of momentum-the fact that the total momentum of a system remains constant unless it is acted upon by an external force.

Isospin symmetry is an important symmetry in particle physics, although it occurs only in the action of the nuclear binding force-or, in modern terminology, the strong force. The symmetry leads to the conservation of isospin in nuclear interactions that occur via the strong force and thereby determines which reactions can occur.