Elementary and subatomic particles
The atom is the smallest particle of matter that cannot be divided by chemical means, but atoms are made up of smaller particles, called subatomic particles. By breaking them down even more, subatomic particles are often made up of elementary particles . Here is an overview of the three main subatomic particles of an atom, their electrical charges, their masses and their properties. From there, discover some key elementary particles.
The most basic unit of an atom is the proton because the number of protons in an atom determines its identity as an element. Technically, a solitary proton can be considered as an atom of an element (hydrogen, in this case).
Net charge: +1
Rest mass: 1.67262 × 10 -27 kg
The atomic nucleus consists of two subatomic particles which are linked together by the strong nuclear force. One of these particles is the proton. The other is the neutron . Neutrons are approximately the same size and mass as protons, but they have no net electrical charge or are electrically neutral . The number of neutrons in an atom does not affect its identity, but determines its isotope .
Net charge: 0 (although each neutron is made up of charged subatomic particles)
Mass at rest: 1.67493 × 10 -27 kg (slightly larger than that of a proton)
The third major type of subatomic particle in an atom is the electron . The electrons are much smaller than protons or neutrons and typically orbit an atomic nucleus at a relatively large distance from its nucleus. To put the size of the electron into perspective, a proton is 1863 times more massive. Because the mass of the electron is so small, only protons and neutrons are considered when calculating the mass number of an atom.
Net charge: -1
Rest mass: 9.10938356 × 10 -31 kg
Because the electron and the proton have opposite charges, they are attracted to each other. It is also important to note that the charge of an electron and a proton, although vice versa, is equal in magnitude. A neutral atom has an equal number of protons and electrons.
Because electrons are orbiting atomic nuclei, it is the subatomic particles that affect chemical reactions. The loss of electrons can lead to the formation of positively charged species called cations. Gaining electrons can yield negative species called anions. Chemistry is essentially the study of the transfer of electrons between atoms and molecules.
Subatomic particles can be classified either as composite particles or as elementary particles. Composite particles are made up of smaller particles. Elementary particles cannot be subdivided into smaller units.
The standard model of physics includes at least:
- 6 quark flavors: high, low, high, low, strange, charge
- 6 types of leptons: electron, muon, tau, electron neutrino, muon neutrino, tau neutrino
- 12-gauge bosons, which include the photon, 3 W and Z bosons and 8 gluons
- the Higgs boson
There are other elementary particles on offer, including graviton and magnetic monopoly.
Thus, the electron is a subatomic particle, an elementary particle and a type of lepton. A proton is a composite subatomic particle composed of two quarks up and one quark down. A neutron is a composite subatomic particle composed of two descending quarks and a quark up.
Hadrons and exotic subatomic particles
The composite particles can also be divided into groups. For example, a hadron is a particle made up of quarks that are held together by strong force in the same way that protons and neutrons bond to form atomic nuclei.
There are two main families of hadrons: baryons and mesons. Baryons are made up of three quarks. The mesons consist of a quark and an anti-quark. In addition, there are exotic hadrons, exotic mesons and exotic baryons, which do not fit the usual definitions of particles.
Protons and neutrons are two types of baryons, and therefore two different hadrons. Pawns are examples of mesons. Although protons are stable particles, neutrons are only stable when bound in atomic nuclei (half-life of about 611 seconds). The other hadrons are unstable.
Even more particles are predicted by theories of supersymmetric physics. Examples include neutralinos, which are superpartners of neutral bosons, and sleptons, which are superpartners of leptons.
In addition, there are antimatter particles corresponding to matter particles. For example, the positron is an elementary particle which is the counterpart of the electron. Like an electron, it has a spin of 1/2 and an identical mass, but it has an electrical charge of +1.
You may also look at Subatomic particles and elementary particles