The binding energy of an atomic nucleus: formula, meaning and definition
Each of the atomic nuclei is absolutelyA chemical substance consists of a specific set of protons and neutrons. They are held together due to the fact that the binding energy of the atomic nucleus is present inside the particle.
A characteristic feature of the nuclear forces of attraction is their very large power at relatively small distances (from about 10-13cm). As the distance between particles increases, the forces of attraction within the atom also weaken.
Reasoning about the binding energy inside the nucleus
If we imagine that there is a way to separate byqueues from the nucleus of the atom, protons and neutrons and locate them at such a distance that the binding energy of the atomic nucleus ceases to operate, then this must be a very hard work. In order to extract its constituents from the nucleus of the atom, it is necessary to try to overcome the intra-atomic forces. These efforts will be to divide the atom into the nucleons contained in it. Therefore, it can be judged that the energy of the atomic nucleus is less than the energy of those particles from which it consists.
Is the mass of interatomic particles equal to the mass of an atom?
Already in 1919, researchers learned to measuremass of the atomic nucleus. Most often it is "weighed" by means of special technical devices, which are called mass spectrometers. The principle of operation of such devices is that the characteristics of the motion of particles with different masses are compared. At the same time, such particles have identical electric charges. Calculations show that those particles that have different mass indicators move along different trajectories.
Modern scientists have found with great accuracythe masses of all nuclei, as well as the protons and neutrons that make up their composition. If we compare the mass of a certain nucleus with the sum of the masses of particles contained in it, it turns out that in each case the mass of the nucleus will be larger than the mass of individual protons and neutrons. This difference is approximately 1% for any chemical. Therefore, we can conclude that the binding energy of the atomic nucleus is 1% of the energy of its rest.
Properties of intranuclear forces
Neutrons that are inside the nucleus,repel each other by Coulomb forces. But the atom does not break up into pieces. This is facilitated by the presence of an attractive force between the particles in the atom. Such forces, which have a nature other than electrical, are called nuclear forces. And the interaction of neutrons and protons is called a strong interaction.
In brief, the properties of nuclear forces are reduced to the following:
- it is charge independence;
- action only at short distances;
- as well as saturation, which refers to the retention of each other only a certain number of nucleons.
By the law of conservation of energy, at the moment when nuclear particles are connected, energy is released in the form of radiation.
The binding energy of atomic nuclei: formula
For the above calculations, the conventional formula is used:
ESt.= (Z · mp+ (A-Z) · mn-MI) · C²
Here underESt.the nuclear binding energy is understood;from- speed of light;Z- number of protons;(A-Z) is the number of neutrons;mpdenotes the mass of the proton; amnIs the neutron mass.MIdenotes the mass of the nucleus of the atom.
The internal energy of the nuclei of various substances
To determine the binding energy of the nucleus, it is usedthe same formula. Calculated by the formula, the binding energy, as was previously indicated, is no more than 1% of the total energy of the atom or rest energy. However, on closer examination, it turns out that this number fluctuates quite strongly when passing from substance to substance. If we try to determine its exact values, then they will be especially different in the so-called light nuclei.
For example, the binding energy inside the hydrogen atom is zero, because there is only one proton in it.The binding energy of the helium nucleus will be 0.74%. In the case of nuclei of matter called tritium, this number will be 0.27%. For oxygen it is 0.85%. In nuclei, where there are about sixty nucleons, the energy of the intra-atomic bond will be about 0.92%. For atomic nuclei with a larger mass, this number will gradually decrease to 0.78%.
To determine the binding energy of the helium, tritium, oxygen, or any other substance, the same formula is used.
Types of protons and neutrons
The main reasons for such differences may beexplained. Scientists have found out that all the nucleons that are contained inside the nucleus fall into two categories: superficial and internal. Internal nucleons are those that are surrounded by other protons and neutrons from all directions. Surface ones are surrounded by them only from the inside.
The binding energy of an atomic nucleus is a force that is greater in internal nucleons. Something like this, by the way, occurs with the surface tension of various liquids.
How many nucleons are placed in the nucleus
It is found that the number of internal nucleonsespecially small in the so-called light nuclei. And for those that belong to the category of the lungs, almost all nucleons are regarded as superficial. It is believed that the binding energy of an atomic nucleus is a quantity that must grow with the number of protons and neutrons. But even such growth can not continue indefinitely. With a certain number of nucleons - and this is from 50 to 60 - another force comes into effect - their electrical repulsion. It occurs even regardless of the presence of binding energy inside the nucleus.
The binding energy of an atomic nucleus in various substances is used by scientists in order to release nuclear energy.
Many scientists have always been interested in the question: where does energy come from when lighter nuclei merge into heavy ones? In fact, this situation is analogous to atomic fission. In the process of fusion of light nuclei, just as it happens during the splitting of heavy nuclei, nuclei of a more durable type are always formed. To "get" out of light nuclei all the nucleons in them, it is required to spend less amount of energy than what is allocated when they are combined. The converse statement is also true. In fact, the energy of synthesis, which accounts for a certain unit of mass, may be greater than the specific energy of fission.
Scientists who studied the processes of nuclear fission
The process of nuclear fission was discovered by the scientists of Ghana andStrassmann in 1938. Within the walls of the Berlin Chemical University, the researchers discovered that in the process of bombarding uranium with other neutrons, it turns into lighter elements in the middle of Mendeleyev's table.
A significant contribution to the development of this field of knowledgeand Lisa Meitner, whom Gan once proposed to study radioactivity together. Gan allowed Meitner to work only on the condition that she would conduct her studies in the basement and never go up to the upper floors, which was a fact of discrimination. However, this did not prevent her from achieving significant successes in the research of the atomic nucleus.