Atomic number refers toelementThe serial number in the periodic table, with the symbol Z, is numerically equal to that of the atomic nucleusNuclear charge number(i.eProton number）Or neutral atomsNumber of electrons。For example, the atomic number of carbon is 6, and its nuclear charge (proton number) or extranuclear electron number is also 6.[1]
Chinese name
Atomic number
Foreign name
atomic number
Definition
Serial number of element in periodic table
Value
be equal toNucleusNuclear charge number of (proton number)
Symbol
Z
Formula
Atomic number=number of nuclear charges=number of extranuclear electrons
Atomic numberIs aNucleuswithinprotonNumber of.People number the elements in the order of nuclear charge from small to large, which is called atomic number.The atomic number of an element is numerically equal to the nuclear charge of the atom of the element.Having the same atomic numberatomThey belong to the same chemical element.The symbol of atomic number isZ。
Atomic structure and expression method
Generally, the atomic number is written at the bottom left of the element symbol.
Element symbolRecord the number of nuclear charges in the lower left corner of[2](i.e. atomic number).Atomic sequence is generally usedZIndicates that it may be from atomic sequenceGermanAtomzahl。But before 1915,GermanZahl(Number) is used to indicate the number of elements in the periodic table.[3]
But because of theAtomic numberIt is always fixed, so this value is seldom written in this way.It is more common to label in isotopes, just like the symbol of the element.
periodic table of ele ments
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periodic table of ele ments
Dmitry MendeleevIn formulating hisperiodic table of ele mentsIt was found that if he arranged the elements according to their nuclear mass, some irregularities would occur.For example, the nucleus of tellurium is heavier than iodine, but fromChemical propertiesTellurium obviously belongs to the same group as oxygen, sulfur and selenium, while iodine belongs to the same group as fluorine, chlorine and bromine, that is, iodine is next to tellurium.1913Henry MosleyThe solution to this anomaly is to arrange it according to the charge number of the nucleus, that is, the atomic number, rather than the atomic weight.[1]
Up to 2007, a total of 118 elements have been found, 94 of which exist on the earth.
chemical property
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Each chemical element has unique chemical properties according to the number of electrons (that is, atomic number) when the element is electrically neutral.ElectronicElectronic layoutaccording toquantum mechanicsThe principle ofElectronic layerThe number of electrons, especially the number of valence electrons, is determined byChemical bondMain factors of characteristics.Therefore, an element can be defined as a mixture of many arbitrary atoms with a specific atomic number.[2]
New Element
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Newly discovered elements are generally represented by their atomic order. By 2010, elements with atomic orders from 1 to 118 have been found.The synthesis of new elements is to use ions to hit target atoms with plateau sub order, and the atomic order of ions and target atoms is equal to the atomic order of the element to be discovered.Generally speaking, when the atomic order is larger, the half-life is shorter, but it may exist for isotopes with specific proton and neutron numbersStable islandIts half-life will be longer than that of elements with the same atomic order.[1]
