Quarks are elementary particles and the basic unit of matter. Quarks combine with each other to form a composite particle called hadron. The most stable hadrons are protons and neutrons, which are the units that make up the nucleus.
Because of a phenomenon called quark confinement, quarks cannot be directly observed or separated; Quarks can only be found in hadrons. It is for this reason that most of our knowledge about quarks comes from the observation of hadrons.
All neutrons are composed of three kinds of quarks, such as protons and neutrons; Antineutrons consist of three corresponding antiquarks. Proton consists of two upper quarks and one lower quark, and neutron consists of two lower quarks and one upper quark.
Quarks have many different intrinsic properties, including charge, color charge, spin and mass. In the standard model, quarks are the only elementary particles that can withstand all four basic interactions, which are sometimes called "fundamental forces" (electromagnetic force, gravity, strong interaction and weak interaction).
Quarks are also the only known elementary charge non-integer particles. Every taste of quark has a corresponding antiparticle, called antiquark, which is different from quark only in that some of its characteristics are the same size as quark, but the sign is different.
Quarks are divided into three generations according to their characteristics, as follows:
Symbol Chinese name English name Charge (E) Mass (GeV/C 2)
Quark up +2/3 0.004 on U
D under quark-1/3 0.008
C charm quark charm +2/3 1.5
s？ Strange quarks? Strange-1/3 0. 15
T-top quark top +2/3 176
B quark bottom-1/3 4.7
Extended data:
The densest and smallest in nature.
1. The densest osmium on the earth is metal, and its density is 22.5× 103kg/m3. But in the vast universe, osmium is simply a tiny one in the "density family". The white dwarfs in the sky are not big, but the density is amazing. This is the density of water. ?
2. In1957, astronomers discovered neutron stars with telescopes, with a density as high as1.0×1017kg/m3. A neutron star material as big as a matchbox and with a mass of 3 billion tons needs more than 96,000 heavy locomotives to pull it.
3. There is a new celestial body in the universe, whose density is higher than that of neutron stars, reaching1.82×1019 kg/m3. It is very attractive to other objects. As long as it is attracted to it, it will swallow even the light. Because it doesn't shine, people give it an image name "black hole" H yuan.
Element is the smallest mass number, and the constituent element is hydrogen?
Hydrogen is the least mass substance in the universe (excluding antimatter)?
What is the most important gas in the three-state change of an object?
So hydrogen is the least dense in the universe?
There is no substance in a vacuum. As long as there is substance, the density will be greater than that in vacuum?
Among all kinds of gases, hydrogen has the lowest density. Under standard conditions, the mass of 1 liter hydrogen is 0.0899 g.
References:
Baidu encyclopedia-quantum