It was once thought that the smallest unitThe structure of any substance is a molecule. Then, with the invention of more powerful microscopes, humanity discovered with astonishment the concept of an atom - a composite particle of molecules. It would seem, much less? Meanwhile, even later it turned out that the atom, in turn, consists of smaller elements.
In the early 20th century, the British physicist RutherfordErnest discovered the presence in the atom of nuclei - the central structures, it was this moment that marked the beginning of a series of endless discoveries concerning the device of the smallest structural element of matter.
To date, based on the nuclear model of atomic structure and through numerous studies, it is known that the atom consists of a nucleus that is surrounded by an electronic cloud. In the composition of such a "cloud" - electrons, or elementary particles with a negative charge. The nucleus, on the contrary, includes particles with an electrically positive charge, called protons. The already mentioned British physicist was ableto observe and subsequently describe this phenomenon. In 1919, he conducted an experiment, which consisted in the fact that alpha particles knocked out hydrogen nuclei from the nuclei of other elements. Thus, he managed to find out and prove that the protons are nothing but the nucleus of a hydrogen atom without a single electron. In modern physics, protons are designated by the symbol p or p + (which means a positive charge).
Proton in Greek means "first, basic" - an elementary particle belonging to the class baryons, those. relatively heavy elementary particles. It is a stable structure, its lifetime is more than 2.9 x 10 (29) years.
Strictly speaking, apart from the proton, the nucleus of the atom also contains neutrons, which, based on the name, are neutrally charged. Both these elements are called nucleons.
The mass of the proton, for quite obvious reasons, could not be measured for a long time. Now we know that it is
mp = 1.67262 ∙ 10-27 kg.
In this way, the rest mass of the proton also looks.
Let us now consider the understanding of the mass of the proton, which are specific for different fields of physics.
The mass of a particle within the framework of nuclear physics often assumes a different form, its unit of measurement is an amu.
A.E. is the atomic mass unit. One amu equals 1/12 of the mass of the carbon atom whose mass number is 12. Hence, the atomic mass unit is 1.66057 · 10-27 kg.
The mass of the proton, therefore, is as follows:
mp = 1.007276 a. eat.
There is another way to express the mass of thispositively charged particle, using other units of measurement. To do this, we first need to take as an axiom the equivalence of mass and energy E = mc2. Where c is the speed of light and m is the mass of the body.
The proton mass in this case will be measured inmegaelectronvolts or MeV. This unit of measurement is used exclusively in nuclear and atomic physics and serves to measure the energy that is required to transport a particle between two points in an electrostatic field. With the condition that the potential difference between these points is 1 Volt.
Hence, taking into account that 1 amu = 931.494829533852 MeV, the mass of the proton is approximately
mp = 938 MeV.
Such a conclusion was obtained on the basis of mass spectroscopic measurements, and it is the mass in the form in which it is given above that it is also customary to call ethe resting quiescence of a proton.
Thus, guided by the needs of the experiment, the mass of the smallest particle can be expressed in three different values, in three different units of measurement.
In addition, the proton mass can be expressedrelative to the mass of the electron, which is known to be much "heavier" than the positively charged particle. Equal mass with a rough calculation and significant errors in this case will be 1836,152 672 relative to the mass of the electron.
