List of subatomic particles
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Subatomic particles of atoms
The following are the basic particles comprising atoms. The proton, neutron, and electron are the fundamental building blocks of atoms.
- nucleus
- A nucleus is the dense central portion of the atom, composed of protons and neutrons. The nucleus of a hydrogen atom, however, consists of just one proton.
- proton
- A proton is a positively charged subatomic particle found in the nucleus of an atom. It has a relative mass of 1 amu (atomic mass unit), or 1.67×10−24 grams. The number of protons (atomic number) in an atom determines the element of that atom. (For example, a hydrogen atom has one proton, a helium atom has two protons, a lithium atom has three protons, et cetera.
- neutron
- A neutron is a subatomic particle with no charge and a mass of 1 amu that is found in the nucleus of an atom. Its mass in grams is 1.67×10−24. The number of neutrons determines the isotope of an atom. Isotopes are atoms of the same element that have the same atomic number but different masses due to a different number of neutrons.
- electron
- An electron is a negatively charged subatomic particle with a relative mass of 1/1840 amu, or 9.11×10−28 grams. Electrons circle around the nucleus of an atom in different levels. The number of electrons in an atom is equal to the number of protons in that same atom, which makes atoms have no charge.
- The electrons in the outermost level are called valence electrons. The number of valence electrons in an atom determines the chemical properties of that element; therefore, elements with the same number of valence electrons have very similar chemical properties. Valence electrons are also shared between atoms or ions to form chemical bonds. The bonds between atoms are called covalent bonds, which connect atoms together to form molecules. The bonds between ions are called ionic bonds, which connect positive ions (cations) and negative ions (anions) together to form ionic compounds (also called formula units). If an atom loses one or more valence electrons, it becomes a cation, or an ion with a positive charge. If an atom gains one or more electrons, it becomes an anion, or an ion with a negative charge.
Subatomic particles of antiatoms
The following are the basic particles comprising antiatoms. They are known as antiparticles. An antiparticle is a subatomic particle identical to another subatomic particle in mass but opposite to it in electric and magnetic properties that when brought together with its counterpart produces mutual annihilation.
- antinucleus
- An antinucleus is the dense central portion of the antiatoms, composed of antiprotons and antineutrons.
- antiproton
- An antiproton is the antiparticle of the proton.
- antineutron
- An antineutron is an uncharged particle of mass equal to that of the neutron but having a magnetic moment in the opposite direction.
- positron (also known as an antielectron)
- A positron is a positively charged particle having the same mass and magnitude of charge as the electron and constituting the antiparticle of the electron.
Other subatomic particles
- quark
- A quark is a hypothetical particle that carries a fractional electric charge. They are thought to come in several types (as up, down, strange, charmed, and bottom) and are believed to be a constituent of hadrons, including protons and neutrons.
- antiquark
- An antiquark is the hypothetical antiparticle of the quark.
- gluon
- A gluon is a hypothetical neutral, massless particle believed to bind together quarks to form hadrons.
- hadron
- A hadron is any of the subatomic particles that take part in the strong interaction. Hadrons include protons and neutrons.
- alpha particle (α-particle)
- An alpha particle is a positively charged nuclear particle identical with the nucleus of a helium atom that consists of two protons and two neutrons and is ejected at high speed in certain radioactive transformations.
- beta particle (β-particle)
- A beta particle is an electron or positron ejected from the nucleus of an atom during radioactive decay. A beta particle can also be a high-speed electron or positron.
- nucleon
- A nucleon is a proton or a neutron, particularly one in the atomic nucleus. However, "nucleon" can also refer to a hypothetical single entity with one-half unit of isospin capable of manifesting itself as either a proton or a neutron and of making transitions between these two states.
- antinucleon
- An antinucleon is the antiparticle of a nucleon.
- neutrino
- A neutrino is an uncharged (having a neutral charge) elementary particle that has at least at two forms and is believed to be massless. Neutrinos interact very weakly after being created as a result of particle decay.
- antineutrino
- An antineutrino is the antiparticle of the neutrino.
- lambda particle (λ-particle)
- A lambda particle is an unstable uncharged elementary particle that has a mass 2,183 times that of an electron and that decays typically into a nucleon and a pion.
- omega minus (ω−)
- An omega minus particle is a negatively charged elementary particle that has a mass 3,270 times the mass of an electron. It decays into a xi particle and a pion.
- positronium
- Positronium is a semistable atomic system formed of an electron and a positron before they interact to annihilate each other.
Mesons
The following is a list of subatomic particles known as mesons. A meson is any of a group of fundamental particles (as the pion and kaon) that are strongly interacting and have zero or an integer number of quantum units of spin.
- J particle (also known as a psi particle, ψ-particle)
- A J particle is an unstable neutral/uncharged fundamental particle of the meson group that has a mass about 6,000 times the mass of an electron.
- kaon (also known as a K-meson)
- A kaon is an unstable meson produced in high-energy particle collisions with its electrically charged forms being 966.3 times more massive than the electron and its neutral form being 974.6 times more massive than the electron.
- omega meson (ω-meson)
- An omega meson is a very short-lived unstable meson with a mass that is 1,532 times the mass of an electron.
- pion (also known as a pi-meson, π-meson)
- A pion is a short-lived meson that is primarily responsible for the nuclear force and that exists as a positive or negative particle with a mass 273.2 times greater than the electron mass or as a neutral particle with a mass 264.2 times greater than the electron mass.
- upsilon particle (υ-particle)
- An upsilon particle is any of a group of electrically neutral elementary particles of the meson family that have a mass about ten times that of a proton.
Baryons
The following is a list of subatomic particles known as baryons. A baryon is any of a group of subatomic particles (as nucleons) that undergo strong interactions and are held to be a combination of three quarks.
- sigma particle (σ-particle)
- A sigma particle is an unstable subatomic particle of the baryon family and exists in positive, negative, and neutral charge states with masses respectively 2328, 2343, and 2333 times the mass of an electron.
Leptons
The following is a list of subatomic particles known as leptons. A lepton is any of a family of particles (as electrons, muon, and neutrinos) that have a spin quantum number of ½ and that experience no strong interactions.
- muon (also known as a mu-meson, μ-meson)
- A muon is an unstable lepton that is common in the cosmic radiation near the earth’s surface. It has a mass that is about 207 times the mass of the electron, and it exists in both negative and positive forms. A muon can combine with an electron, creating a short-lived quasi-atom called muonium.
- tau particle (τ-particle)
- A tau particle is a short-lived elementary particle of the lepton family that exists in both positive and negative charge states and has a mass about 3,500 times heavier than an electron.