Isotopes

Atoms of the same element that have different mass numbers are called isotopes. Atoms of isotopes of the same element have the same number of protons (Z) and differ from each other in the number of neutrons (N).

Isotopes of various elements do not have their own names, but repeat the name of the element; in this case, the atomic mass of a given isotope - its only difference from other isotopes of the same element - is reflected using a superscript in the chemical formula of the element: for example, for uranium isotopes - 235 U, 238 U. The only exception to the rules of isotope nomenclature is element No. 1 - hydrogen. All three currently known isotopes of hydrogen have not only their own special chemical symbols, but also their own name: 1 H - protium, 2 D - deuterium, 3 T - tritium; in this case, the protium nucleus is simply one proton, the deuterium nucleus contains one proton and one neutron, the tritium nucleus contains one proton and two neutrons. The names of hydrogen isotopes have historically developed this way because the relative difference in the masses of hydrogen isotopes caused by the addition of one neutron is the maximum among all chemical elements.

All isotopes can be divided into stable (stable), that is, not subject to spontaneous decay of atomic nuclei into parts (decay in this case is called radioactive), and unstable (unstable) - radioactive, that is, subject to radioactive decay. Most elements widespread in nature consist of a mixture of two or more stable isotopes: for example, 16 O, 12 C. Of all the elements, tin has the largest number of stable isotopes (10 isotopes), and, for example, aluminum exists in nature in the form of only one stable isotope - the rest of its known isotopes are unstable. The nuclei of unstable isotopes decay spontaneously, releasing b particles and c particles (electrons) until a stable isotope of another element is formed: for example, the decay of 238 U (radioactive uranium) ends with the formation of 206 Pb (a stable isotope of lead). When studying isotopes, it was found that they do not differ in chemical properties, which, as we know, are determined by the charge of their nuclei and do not depend on the mass of the nuclei.

Electronic shells

The electron shell of an atom is a region of space where electrons are likely to be located, characterized by the same value of the principal quantum number n and, as a consequence, located at close energy levels. Each electron shell can have a certain maximum number of electrons.

Starting from the value of the main quantum number n = 1, the energy levels (layers) are designated K, L, M and N. They are divided into sublevels (sublayers) that differ from each other in the binding energy with the nucleus. The number of sublevels is equal to the value of the main quantum number, but does not exceed four: the 1st level has one sublevel, the 2nd - two, the 3rd - three, the 4th - four sublevels. Sublevels, in turn, consist of orbitals. It is customary to denote sublevels with Latin letters, s is the first sublevel of each energy level closest to the nucleus; it consists of one s-orbital, p - the second sublevel, consists of three p-orbitals; d is the third sublevel, it consists of five d-orbitals; f is the fourth sublevel, contains seven f orbitals. Thus, for each value of n there are n 2 orbitals. Each orbital can contain no more than two electrons - the Pauli principle. If there is one electron in an orbital, then it is called unpaired; if there are two, then these are paired electrons. The Pauli principle explains the formula N=2n 2. If the first level K(n=1) contains 1 2 = 1 orbital, and each orbital has 2 electrons, then the maximum number of electrons will be 2*1 2 =2; L (n = 2) =8; M (n = 3) =18; N (n = 4) =32.

It has been established that every chemical element found in nature is a mixture of isotopes (hence they have fractional atomic masses). To understand how isotopes differ from one another, it is necessary to consider in detail the structure of the atom. An atom forms a nucleus and an electron cloud. The mass of an atom is influenced by electrons moving at stunning speeds through orbitals in the electron cloud, neutrons and protons that make up the nucleus.

Definition

Isotopes is a type of atom of a chemical element. There are always equal numbers of electrons and protons in any atom. Since they have opposite charges (electrons are negative, and protons are positive), the atom is always neutral (this elementary particle does not carry a charge, it is equal to zero). When an electron is lost or captured, an atom loses neutrality, becoming either a negative or a positive ion.

Neutrons have no charge, but their number in the atomic nucleus of the same element can vary. This does not in any way affect the neutrality of the atom, but it does affect its mass and properties. For example, any isotope of a hydrogen atom contains one electron and one proton. But the number of neutrons is different. Protium has only 1 neutron, deuterium has 2 neutrons, and tritium has 3 neutrons. These three isotopes differ markedly from each other in properties.

Comparison

They have different numbers of neutrons, different masses and different properties. Isotopes have identical structures of electron shells. This means that they are quite similar in chemical properties. Therefore, they are given one place in the periodic table.

Stable and radioactive (unstable) isotopes have been found in nature. The nuclei of atoms of radioactive isotopes are capable of spontaneously transforming into other nuclei. During the process of radioactive decay, they emit various particles.

Most elements have over two dozen radioactive isotopes. In addition, radioactive isotopes are artificially synthesized for absolutely all elements. In a natural mixture of isotopes, their content varies slightly.

The existence of isotopes made it possible to understand why, in some cases, elements with lower atomic mass have a higher atomic number than elements with higher atomic mass. For example, in the argon-potassium pair, argon includes heavy isotopes, and potassium contains light isotopes. Therefore, the mass of argon is greater than that of potassium.

Conclusions website

1. They have different numbers of neutrons.
2. Isotopes have different atomic masses.
3. The value of the mass of ion atoms affects their total energy and properties.

It has been established that every chemical element found in nature is a mixture of isotopes (hence they have fractional atomic masses). To understand how isotopes differ from one another, it is necessary to consider in detail the structure of the atom. An atom forms a nucleus and an electron cloud. The mass of an atom is influenced by electrons moving at stunning speeds through orbitals in the electron cloud, neutrons and protons that make up the nucleus.

What are isotopes

Isotopes is a type of atom of a chemical element. There are always equal numbers of electrons and protons in any atom. Since they have opposite charges (electrons are negative, and protons are positive), the atom is always neutral (this elementary particle does not carry a charge, it is equal to zero). When an electron is lost or captured, an atom loses neutrality, becoming either a negative or a positive ion.
Neutrons have no charge, but their number in the atomic nucleus of the same element can vary. This does not in any way affect the neutrality of the atom, but it does affect its mass and properties. For example, any isotope of a hydrogen atom contains one electron and one proton. But the number of neutrons is different. Protium has only 1 neutron, deuterium has 2 neutrons, and tritium has 3 neutrons. These three isotopes differ markedly from each other in properties.

Comparison of isotopes

How are isotopes different? They have different numbers of neutrons, different masses and different properties. Isotopes have identical structures of electron shells. This means that they are quite similar in chemical properties. Therefore, they are given one place in the periodic table.
Stable and radioactive (unstable) isotopes have been found in nature. The nuclei of atoms of radioactive isotopes are capable of spontaneously transforming into other nuclei. During the process of radioactive decay, they emit various particles.
Most elements have over two dozen radioactive isotopes. In addition, radioactive isotopes are artificially synthesized for absolutely all elements. In a natural mixture of isotopes, their content varies slightly.
The existence of isotopes made it possible to understand why, in some cases, elements with lower atomic mass have a higher atomic number than elements with higher atomic mass. For example, in the argon-potassium pair, argon includes heavy isotopes, and potassium contains light isotopes. Therefore, the mass of argon is greater than that of potassium.

TheDifference.ru determined that the difference between isotopes is as follows:

They have different numbers of neutrons.
Isotopes have different atomic masses.
The value of the mass of ion atoms affects their total energy and properties.