The composition of the nucleus of the atom. A calculation of protons and neutrons

According to the modern concepts, the atom consists of a nucleus and electrons that surround it. The nucleus of the atom, in its turn, consists of smaller elementary particles - a certain number of protons and neutrons (which are commonly referred to as nucleons), interconnected by nuclear forces.

The number of protons in the nucleus determines the structure of the electron shell of an atom. And, the electron shell determines the physical and chemical properties of the substance. The number of protons corresponds to the serial number of an atom in the periodic system of chemical elements developed by Mendeleev, also known as the charged number, atomic number, atomic numeral. For example, the atom of helium has 2 protons. It is placed under number 2 in the periodic system, and is denoted as He2. The Latin letter Z is used as a symbol to indicate the number of protons. When recording the formulas, often the number, indicating the amount of protons, is located below the symbol of the element either to the right, or to the left: He2 / 2He.

The number of neutrons corresponds to a certain isotope of this or that element. Isotopes are the elements with the equal atomic number (the equal number of protons and electrons) but with different mass numbers. The mass number is the total number of neutrons and protons in the nucleus of an atom (is denoted by a Latin letter A). When recording the formulas the mass number is indicated at the top of the element symbol on one side or another: He42/42He (helium isotope is helium -4)


 

Thus, to identify the number of neutrons in a particular isotope, the number of protons should be subtracted from the total mass number. For example, we know that an atom of helium-4 He42 has 4 elementary particles as the mass number of the isotope is 4. At the same time, we know that He42 has 2 protons. Having subtracted 2 (the number of protons) from 4 (the total mass number) we get 2- the number of neutrons in the nucleus of helium-4.


 

PROCESS OF CALCULATION OF THE NUMBER OF PHANTOM PO PARTICLES IN NUCLEUS OF THE ATOM. As an example, it is no coincidence that we have considered Helium-4 (He42), the nucleus of which consists of two protons and two neutrons. As helium-4 nucleus, called as alpha particle (α-particle), has the highest efficiency in nuclear reactions, it is often used for experiments in this direction. It is worth noting that symbol α is often used instead of He42 in the formulas of the nuclear reactions.


 

Reserford conducted the first reaction of nuclear transformation that is known in the official history of physics, exactly with the involvement of alpha particles. In the course of reaction, the nucleus of the isotope of nitrogen (N147) were "hit" by α-particles (He42) and as a result isotope of oxygen (O178) and one proton (p11) were produced.

This nuclear reaction is as follows:


 

We conduct a calculation of the number of phantom Po particles before and after this transformation.


 

THE FOLLOWING STEPS ARE REQUIRED TO CALCULATE THE NUMBER OF PHANTOM PO PARTICLES
Step 1. To calculate the number of neutrons and protons in each nucleus:
- The number of protons is in the bottom indicator;
- We will get the number of neutrons, by subtracting the number of protons (the lower indicator) from the total mass number (top indicator).

Step 2. To calculate the number of phantom Po particles in nucleus of the atom:
- to multiply the number of protons by the number of phantom Po particles contained in one proton
- to multiply the number of neutrons by the number of phantom Po particles contained in one neutron;

Step 3. To sum up the number of phantom Po particles:
- to sum up the number of phantom Po particles thus calculated in the protons with the calculated number of phantom Po particles in the neutrons in the nuclei before the reaction;
- to sum up the number of phantom Po particles thus calculated in the protons with calculated number of phantom Po particles in the neutrons in the nuclei after the reaction.
- to compare the number of phantom Po particles before the reaction with the number of phantom Po particles after reaction.


 

EXAMPLE OF DETAILED CALCULATION OF THE NUMBER OF PHANTOM PO PARTICLES IN ATOMIC NUCLEI.
(The nuclear reaction with α-particles (He42), conducted by E. Reserford in 1919)

BEFORE THE REACTION: (N147 + He42)
N147

Number of protons: 7
Number of neutrons: 14-7 = 7
Number of phantom Po particles:
In 1 proton there are 12 Po, hence in 7 protons: (12 х 7) = 84;
In 1 neutron there are 33 Po, hence in 7 neutrons: (33 х 7) = 231;
The total number of phantom Po particles in nucleon is: 84+231 = 315

He42
Number of protons – 2
Number of neutrons 4-2 = 2
Number of phantom Po particles:
In 1 proton there are12 Po, hence in 2 protons: (12 х 2) = 24
In 1 neutron there are 33 Po, hence in 2 neutrons: (33 х 2) = 66
The total number of phantom Po particles in nucleon is: 24+66 = 90


 

The number of phantom Po particles before the reaction

N147 + He42
315 + 90 = 405

AFTER THE REACTION (O178) и один протон (p11):
O178
Number of protons: 8
Number of neutrons: 17-8 = 9
Number of phantom Po particles:
In 1 proton there are 12 Po, hence in 8 protons: (12 х 8) = 96
In 1 neutron there are 33 Po, hence in 9 neutrons: (9 х 33) = 297
The total number of phantom Po particles the nucleus is: 96+297 = 393

p11
Number of protons: 1
Number of neutrons: 1-1=0
Number of phantom Po particles:
There are 12 Po in 1 proton.
There are no neutrons.
Total number of phantom Po particles in nucleon is 12


 

Totally, the number of phantom Po particles after reaction is:
(O178 + p11):
393 + 12 = 405

Let us compare the number of phantom Po particles before and after the reaction:


Before After
405 405

The number of phantom Po particles before and after the reaction is equal.


 


 

HERE IS AN EXAMPLE OF THE СONCISE FORM OF CALCULATING THE NUMBER OF PHANTOM PO PARTICLES IN NUCLEAR REACTION.

Here and further the calculations of the number of phantom Po particles are given in a concise form, which displays the total number of phantom Po particles in each nucleus as well as their sum before and after the reaction.

The well-known nuclear reaction is the reaction of interaction of α-particles with an isotope of beryllium, in the course of which neutron was discovered for the first time. It manifested itself as an independent particle as a result of nuclear transformation. This reaction was carried out in 1932 by an English physicist James Chedwick. The formula of the reaction is:

213 + 90 → 270 + 33 - the number of the phantom Po particles in each nucleus

303 = 303 - the total number of phantom Po particles before and after reaction

The number of phantom Po particles before and after reaction is equal.


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