Ch+30+-+Elem+Particles

__Nuclear Fission__ Defined as the splitting of a large nucleus into two smaller nuclei. Normally, fission occurs when a neutron is targeted at a "target" nucleus, which is normally the nucleus of an unstable atom. The most typical example of nuclear fission is that of uranium-235.

In this example, a neutron is targeted at Uranium-235. The Uranium-235 temporarily becomes Uranium-236. Then the Uranium-235 fissions into Barium-141 and Krypton- 92 and three free neutrons. Barium-141 and Krypton-92 are called fission fragments.

A chain reaction occurs when these free neutrons target other Uranium-235 nuclei and cause them to fission. This process will continue to occur until the free neutrons fail to hit Uranium-235 nuclei.

Nuclear reactors are systems designed to maintain self-sustained chain reactions. The first self-sustained chain reaction was performed at the University of Chicago and was led by Fermi.

__Nuclear Fusion__ Nuclear fusion is exactly what the name implies, a fusion of nuclear particles. In a fusion reaction hydrogen atoms are given large amounts of energy via high voltage and superheating. This causes the hydrogen atoms to begin combining into Helium atoms. This releases a certain amount of energy per reaction because the mass of the resulting Helium atom is less than the initial mass of the two Hydrogen atoms. This process, in theory, is very favorable because there is a ton of hydrogen in the universe and the resulting helium is not dangerous. In practicality this process is not efficient. The problem is that the reaction must be contained within a very strong magnetic field produced by large electromagnets. Between the energy needed to power the electromagnets and the energy needed to cause the hydrogen to fusion, too much energy is used and the system doesn't even break even.

__Elementary Particles__ In chemistry, you learned that protons, neutrons, and electrons make up everything in the universe. Chapter 30 is devoted to reteaching you this erroneous theory. Matter is made up of quarks, leptons, and force carriers or bosons

__Anti-particles__ When learning about beta decay in the last chapter, particularly positron decay, you saw that a bi-product of the decay was an anti-electron. Every particle has an anti-particle, which has the same mass as particle, but has an opposite charge. Anti particles make up a substance known as antimatter. Antimatter and matter will annihilate one another when they come in contact.

__Quarks__

There are six types of quarks: up(+2/3), down(-1/3), strange(-1/3), charmed(+2/3), top(+2/3), and bottom(-1/3). There are also six anti-quarks anti-up(-2/3), anti-down(+1/3), anti-strange(+1/3), anti-charmed(-2/3), anti-top(-2/3), and anti-bottom(+1/3).

There are particles that are made up of quarks, which are called hadrons. There are two types of hadrons, baryons and meson. Baryons are made up of three quarks, and mesons are made up of two quarks. Typically mesons are made up of a quark and an anti-quark. The three types of mesons: the pion, kaon, and eta. There are six types of baryons: the proton, neutron, lambda, sigma, xi, and omega.

To see the composition of hadrons, refer to table 30.4 on page 953 of the Physics Book. To see a list of the properties of hadrons, refer to Table 30.2 on page 948 of the text book.

By adding the charges of the quarks that make up a hadron, you can find the charge of a hadron. For instance, protons are made up of two ups and a down quark. Up quarks, as mentioned above have a charge of +2/3 and down quarks have a charge of -1/3. The charge of a proton would then be +2/3 + +2/3 + -1/3, which equals 1. This is why the charge of a proton is +1.

Neutrons are made up of an up quark and two down quarks. The charge of a neutron is therefore +2/3 + -1/3 + -1/3= 0. This is why the charge of a neutron is 0.

Like energy, mass and charge, conservation laws govern all reactions even on a fundamental level. If two particles react with one another the number of each type of quark before hand must equal that same number of quarks afterwords.

__Leptons__ Leptons are smaller than quarks. there are six leptons, and all of them have anti-particles. The six leptons include the electron, electron-neutrino, muon, muon-neutrino, tau, and tau-neutrino. Each lepton particle also has an anti-particle. They are: positrons, positron neutrinos, anti-muons and anti-muon neutrinos, as well as anti-tau and anti-tau neutrinos.

Electrons are the most common types of leptons in the universe and they are also the smallest. Muons and Tau particles both decay until they are eventually electrons

The list of properties of the types of leptons can be found on Table 30.2 on page 948 of the book.

__Quark and lepton calculations__ When making calculations with equations containing quarks and leptons, the laws of conservation of strangeness, charmness, baryon number, electron-lepton number, muon-lepton number, and tau-lepton number must be followed.

__Force Carriers__(also known as bosons) There are four types of naturally occurring forces: Gravitational, Nuclear Strong Force, Nuclear Weak Force, and Electromagnetic Force. The Electromagnetic Force and Nuclear Weak Force are often combined to make the electroweak force. This is done because their bosons are very similar. Forces are held together by bosons. The gravitational force is proposed to be held together by the graviton. The existence of the graviton has not been proven yet, however. The Strong Force is held together by Gluons. The Electroweak Force is held together by three types of bosons: W+, W-, and Z-not.