Proton (from the Greek. protos - first) - positively charged elementary particle, which is part of the nuclei of any chemical elements.
Proton - heavy particle, its weight around 1840 times the mass of the electron (see atomic Nucleus) and is 1,67·10-24 , Radius P. - about 10-13 see the ratio of the size and weight leads to a very large density of the substance P. - about 2·10to 14 g/cm3. A cube with edge 1 cm, consisting of substance P., weighed about 200 000 000 tons
The proton charge is equal to the charge of the electron. The number of P. in the nucleus (atomic number) sets the positive charge on the nucleus and all chemical properties of the corresponding element.
In the simplest atom, hydrogen nucleus consists of one proton and electron shell of the atom, turning one electron.
The size of the hydrogen atom is about 10-8 cm, which is about 100 000 times the size of a proton.
When passing through matter positively charged proton produces ionization of atoms in the medium.
The penetrating power of proton completely determined by its energy (see Proton radiation). At medium energies protons have a negligible penetration ability. However, accelerated to high energies, such as accelerators or in the composition of primary cosmic rays (see), P. can penetrate the protective cover of the skin and create serious biological hazard.