Proton weight

It was once thought that the smallest unit of the 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 Rutherford Ernest discovered the presence of nuclei in the atom - 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 the structure of atoms and due to numerous studies, it is known that the atom consists of a nucleus, which is surrounded by an electron 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 able to 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 positive charge).

Proton in Greek means "first, basic" - an elementary particle belonging to the class of baryons, i.e. 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 proton mass, 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, 1 atomic mass unit is equal to 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 this positively 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 in megaelectronvolts 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, given 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 also the mass in the form in which it was given above that it is also customary to call the quiescent proton energy .

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 mass of the proton can be expressed relative 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.