The arrangement of the electron shell is 2n 2 then why can t the outermost shell exceed 8

The reason why it is 2n 2 is because there are sublayers in each electron shell, the first shell has 1 sublayer 1s, the second shell has two 2s and 2p, and so on, d, f, g, etc., respectively;

The s subshell has an orbital that can be filled with 2 electrons;

The p subshell has three orbitals and can be filled with 6 electrons;

The d subshell has five orbitals and can be filled with 10 electrons;

The f sublayer has seven orbitals and can be filled with 14 electrons;

The g sublayer has nine orbitals and can be filled with 18 electrons;

This adds up to exactly 2n 2;

According to the energy level table, the electrons are arranged in order from lowest to highest, and their order is:

It can be seen that each D sublayer is filled with the S sublayer of the next layer first, so there is no phenomenon of more than 8 electrons.

Because in the electronic configuration, we have to follow the principle of energy level magnitude, minimum energy.

Each electron shell n is composed of electronic sublayers such as s, p, d, f, etc., and the number of electron sublayers is n, which containsorbitals, each orbital holds two electrons. Now the maximum number of electrons or grips in each electron layer is to add these to the group, i.e. (1+3+5+.).

2n-1）=2n2

The outermost shell with an electron number of 2 is distributed in the s region.

1. The number of electrons is the number of electrons. An electron is a fundamental particle, and in chemistry, the number of electrons generally refers to the number of electrons outside the nucleus of an atom or ion. The number of electrons outside the nucleus of an atom = atomic number = the number of protons in the nucleus = the number of nuclear charges (the number of electrons outside the nucleus of an ion = the atomic number (sum) - the number of charges carried.

2. The maximum number of electrons contained in each electron shell is 2n 2 (n is the number of the electronic shell). The number of electrons in the outermost shell does not exceed 8 (no more than 2 when the k-layer is the outermost). The number of electrons in the subouter shell does not exceed 18, and the number of electrons in the penultimate shell does not exceed 32.

Electrons outside the nucleus are always arranged in the lowest energy electron shell first, and then from the inside out, the L layer is arranged before the M layer. The above four laws are interrelated and cannot be understood in isolation.

3. Some properties of matter are determined by its microstructure (four determinations): the number of electrons in the outermost shell determines the chemical properties of the element. Such as:

The outermost electron number of noble gas atoms reaches a stable structure, and their chemical properties are stable, while the outermost electron number of metal and non-metal atoms does not reach a stable structure, so their chemical properties are active.

4. The number of electrons in the outermost shell determines the highest positive or lowest negative valence of the element. For example, the outermost electron number of sulfur is 6, its highest positive valence is +6, and its lowest negative valence is 2;The number of protons in the nucleus determines the type of element, for example, the element with proton number 13 is aluminum. The number of neutrons affects the relative atomic mass of an element (relative atomic mass = number of protons + number of neutrons).

If the number of protons of sodium is 11 and the number of neutrons is 12, then the relative atomic mass of sodium is 23.

Answer C According to the law of extranuclear electron configuration, the outermost shell does not exceed 8 electrons, the subouter shell does not exceed 18 electrons, while the k layer can hold up to 2 electrons, the l layer can hold up to 8 electrons, and the m layer can hold up to 18 electrons When n is the outermost shell, with a maximum of 8 electrons, then the (n-1) layer can also hold 8 electrons, and the (n-1) layer is the secondary outer shell, then the n layer should be the m layer; When n is a secondary outer shell and its maximum number of electrons is 10 more than that of the (n-1) layer, it proves that the n layer can hold up to 18 electrons and should also be m-layer

It depends on whether it is a primary or secondary element.

1. Main family elements.

For the main group elements, the configuration of the outermost electrons and the configuration of the outer electrons mean the same thing.

The outer electrons, i.e., the peripheral electrons, are the characteristic electrons.

2. Paragroup elements.

For subgroup elements, the outermost electrons refer to the electrons of the outermost electron shell;

Outer electrons refer to the outer shell plus part of the electrons of the subouter shell. That is, it is commonly said that the characteristic electrons, peripheral electrons, and outer electrons.

For example, Fe atom:

The outer electron configuration is: 3d6 4s2

The outermost electron configuration is: 4s2

First of all, the number of saturated electrons in atomic orbitals from the inside to the outside is 2, 8, 8 respectively (half of the commonly used atomic orbitals are atomic orbitals).

In terms of the atomic number, that is, the number of nuclear charges. For example, c has six nuclear charges, which is 2 (the first orbital) + 4 (the second orbital, which is the outermost orbital of c), so the outermost electron number of c is 4

In example, CL. The number of nuclear charges is 17, so it is 2 (one) + 8 (two) + 7 (outermost shell) so the outermost electron number of Cl is 7

And so on, you can know the outermost layer.

Add the number of electrons in each of the outermost subshells.

Well, that's what it looks like.

The outer layer includes the outermost layer

Each spine electron shell n is composed of electronic sublayers such as s, p, d, f, etc., and the number of electron sublayers is n, which contains ...orbitals, each orbital holds two electrons. Now the maximum number of electrons next to each electron layer is to add these, that is, (1+3+5+...)

2n-1）=2n2