Although the English name of atom (atom) is intended to be the smallest particle that cannot be further divided, with the development of science, atoms are considered to be composed of electrons, protons, and neutrons (hydrogen atoms are composed of protons and electrons). Collectively referred to as subatomic particles. Almost all atoms contain the above three subatomic particles, but protium (isotope of hydrogen) has no neutrons, and its ion (after losing an electron) is just a proton.
The proton has a positive charge and its mass is 1836 times the mass of the electron, which is 1.6726×10⁻²⁷ kg. However, part of the mass can be converted into atomic binding energy. Neutrons have no charge, and the mass of free neutrons is 1839 times the mass of electrons, which is 1.6929×10⁻²⁷ kg. The sizes of neutrons and protons are similar, both on the order of 2.5×10⁻¹⁵ m, but their surfaces are not precisely defined.
Although atoms are small, they cannot be subdivided by chemical methods, but they can still be subdivided by other methods, because atoms also have a certain composition. Atoms are composed of a positively charged nucleus in the center and negatively charged electrons outside the nucleus (the opposite of antimatter). The nucleus is composed of protons and neutrons. The electrons move at high speeds in a larger space outside the nucleus.
In the standard model theory of physics, both protons and neutrons are composed of elementary particles called quarks. Quark is a kind of fermion and one of the two basic components of matter. Another basic component is called leptons, and electrons are a type of leptons. There are six types of quarks, each of which has a fractional charge, either +2/3 or -1/3. A proton is composed of two up quarks and one down quark, while a neutron is composed of one up quark and two down quarks. This difference explains why the charge and mass of neutrons and protons are different. Quarks are held together by strong interactions and are mediated by gluons. The gluon is a member of the normative boson, a kind of elementary particle used to transmit force.
Subatomic particles have quantization characteristics and wave-particle duality. The formula is expressed as: λ=h/p=h/mv, where λ is wavelength, p is momentum, and h is Planck's constant (6.626×10⁻³⁴ J·S)