Short guide of subatomic particles: quarks and leptons
As we know from high school science class, atom consists of a nucleus comprised of neutrons and protons and nucleus is surrounded by electrons. But what are protons, neutrons and electrons made of?
Proton is made of two types of elementary particles: one "down quark" and two "up quark". There are six types of quarks. Whereas, neutron is also made of quarks but from two "down quark" and one "up quark". Charge of "up quark" is positive 2/3rd of electron where for "down quark" it's negative 1/3rd of electron. And hence protons are positive and neutrons are neutral.
Quarks can not exist as individual particles like electron does, and always found in combination known as hadrons. Protons and neutrons are hadrons. Quarks, are help together by strong interaction via exchange of gluons. Now hadrons can interact with each other by exchanging mesons. And due to this interaction between hadrons via mesons we have protons and neutrons staying inside of a nucleus.
But what about electrons? Electron in an elementary particle in itself and cannot be broken down further. In fact electron is one of the six elementary particles classified under Leptons. 6 leptons and 6 quarks have 1/2 spin and are Fermions. Fermions refer to particles which follow Fermi-statistics. So matter constituents are leptons and quarks.
There is a one more set of elementary particles which have 1 spin and follow Bose-Einstein statistics. Such particles are known as bosons. There are four types of bosons (higgs, photon, W- and W+). These bosons do not form atom but are force carriers. It is through these bosons that particle interact via electroweak and electromagnetic forces.
One interesting thing to note is that each elementary particle as corresponding anti-particle. Anti-particle have same mass and spin but opposite charge. Attached below is summary of matter constituents forming atom.
Proton is made of two types of elementary particles: one "down quark" and two "up quark". There are six types of quarks. Whereas, neutron is also made of quarks but from two "down quark" and one "up quark". Charge of "up quark" is positive 2/3rd of electron where for "down quark" it's negative 1/3rd of electron. And hence protons are positive and neutrons are neutral.
Quarks can not exist as individual particles like electron does, and always found in combination known as hadrons. Protons and neutrons are hadrons. Quarks, are help together by strong interaction via exchange of gluons. Now hadrons can interact with each other by exchanging mesons. And due to this interaction between hadrons via mesons we have protons and neutrons staying inside of a nucleus.
But what about electrons? Electron in an elementary particle in itself and cannot be broken down further. In fact electron is one of the six elementary particles classified under Leptons. 6 leptons and 6 quarks have 1/2 spin and are Fermions. Fermions refer to particles which follow Fermi-statistics. So matter constituents are leptons and quarks.
There is a one more set of elementary particles which have 1 spin and follow Bose-Einstein statistics. Such particles are known as bosons. There are four types of bosons (higgs, photon, W- and W+). These bosons do not form atom but are force carriers. It is through these bosons that particle interact via electroweak and electromagnetic forces.
One interesting thing to note is that each elementary particle as corresponding anti-particle. Anti-particle have same mass and spin but opposite charge. Attached below is summary of matter constituents forming atom.
(Source of image: http://apchemcyhs.wikispaces.com/Subatomic+Particles)
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