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Atomic core: in atoms,NucleusAnd other inner electrons except valence electrons, and inner electrons with the same closed electronic configuration as the corresponding inert elements constitute atomic solids.
For example, sodium NaExtranuclear electron arrangementIs: 1stwo2stwo2psix3sone, in which the first and second electron layers and the atomic nucleus form an atomic solid, which is connected with neon Ne (1stwo2stwo2psix）The structure of sodium is the same, and the arrangement of extranuclear electrons of sodium can also be written as [Ne] 3sone。
The electronic arrangement of potassium K is: 1stwo2stwo2psix3stwo3psix4sone, can also write [Ar] 4sone。
Copper Cu: 1stwo2stwo2psix3stwo3psix3dten4sone, can also write [Ar] 3dten4sone。
They are two basic concepts in atomic physics. They have certain connections and differences.For this reason, we hereby make a systematic introduction to the concept of "atomic reality", aiming to enable some readers to understand the full connotation and extension of the concept of atomic reality, and then find out the difference and relationship between atomic nucleus and atomic reality.
Nucleus
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Nucleus(atomic nucleus) is the central body of the atom. It existed as early as 1911 as Rutherford'sParticle scattering experimentConfirmed.The nucleus consists of positively charged protons and neutral neutrons (collectivelynucleon）They are combined by the nuclear force and generally become a stable combination.
The shape of the atomic nucleus is close to a sphere, and the size of the atomic nucleus is usually expressed by the radius of the atomic nucleus, whose order of magnitude is meters. The specific formula can be as follows:
R=rzeroA1/3
To calculate.WhereRIs the radius of the atomic nucleus (radius of nuclear force action),rzeroIt can be approximately regarded as a constant, and the measured value is 1.20 × 10-15Meters,AIs the mass number of the nucleus in question.
Most elements in nature have stable nuclei, but the nuclei of heavy elements with high atomic numbers are very unstable.In addition, useHigh-energy particleBombing a stable nucleus can produce artificial nuclei.There are more than 2500 known atomic nuclei, of which about 300 are stable and the rest are all unstable.
According to the "planetary atomic model", the atom of any element is composed of a nucleus and electrons outside the nucleus that are distributed in a series of orbits and move around the nucleus according to certain laws.So what does "atomic reality" really mean?in short,Atomic particleIt refers to the rest of the atom except the valence electrons.The valence electrons of an atom generally refer to the electrons in the outermost layer of the atom that can participate in chemical bonds.
The atomic number is equal to the total number of electrons in the atom. It is no accident that it can be listed in such a neat form, which represents the regular combination of electrons in the atom.One common feature of these combinations is that there is an extra electron in addition to a complete structure.This complete and stable structure is called atomic solid.For example, the atom of lithium is composed of its nucleus and two electrons outside the nucleus, while the atom of sodium is composed of its nucleus and 10 electrons outside the nucleus, and so on.[1]
Sports mode
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All inner electrons of alkali metal atoms move around the nucleus along symmetric orbits, so on average, it can be considered that their charges are evenly distributed on one or several spheres with different radii centered on the atomic nucleus, and the negative charge center overlaps the atomic center (i.e. the positive charge center). For the outermost valence electrons,They play the role of shielding the positive charge of the atomic nucleus.Therefore, we can approximately assume that the Z-1 electron and the nucleus together form a "whole" with positive charge+e.Obviously, for this case, the shielding constantλIt is Z-1,Effective nuclear chargeZ *=1, and the so-called "whole" here is the "atomic real" defined above, just from the perspective of electrical equivalence.It can be seen that, from the perspective of electronegativity equivalence, "atomic core" can be equivalent to an atomic nucleus, and the nuclear charge of this atomic nucleus is the effective nuclear charge Z *=Z -λ。In the formula, the shielding constantλSlater, J. C, 1900.12.22~1976.7.25, has concluded a set of methods based on spectral data.[1]
Connection and difference
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To sum up, there are the following connections and differences between atomic nucleus and atomic reality:
(1) Both nuclei and atomic solids contain positive charges and are part of atoms, but nuclei do not include negative charges and atomic solids generally include negative charges, and the number of negative charges is always less than the number of positive charges.
(2) From the perspective of the equivalence of electrical properties, the atomic core is an equivalent atomic core, and the real atomic core is a special atomic core.For example, the nucleus of a hydrogen atom is a special atomic particle (excluding negative charge) for its outer valence electrons.
(3) An atom consists of a nucleus and other extranuclear electrons except one of the outermost valence electrons. It is a complete and stable structural whole between the nucleus and the atom.
(4) Nuclear decay (including artificial).In addition, the nucleus can also produce fission (heavy nucleus) and fusion (light nucleus), thus obtaining huge atomic energy.As an equivalent atomic nucleus, the atomic core has a special phenomenon - polarization of the atomic core. The degree of polarization of the atomic core is closely related to the shape and energy of the valence electron orbit outside the atomic core.
