For the extranuclear electron configuration of an element atom, the number of extranuclear electrons (i.e., atomic number, proton number and nuclear charge number) of the atom is determined first, for example, the total number of extranuclear electrons of Fe-26 element is 26, and then these 26 electrons are arranged in turn from the sublayer with the lowest energy of 1 to the sublayer with higher energy. Only after the previous sublayer is filled,

Iron is widely distributed in life, accounting for 4.75% of the earth's crust content, second only to oxygen, silicon and aluminum, ranking fourth in the earth's crust content. Pure iron is a silvery white metal with good flexibility and ductility, which is used to make iron cores of generators and motors. Iron and its compounds are also used to make magnets, medicines, inks, pigments and abrasives.

Extended data

The relationship between the extranuclear electron configuration of the atom and the orbital expression and the schematic diagram of the atomic structure: The arrangement of the extranuclear electrons of the atom is exactly the same as that described in the orbital expression.

Relatively speaking, the orbital expression is more detailed, which can not only clearly indicate which electron layers and electron sublayers the extranuclear electron configuration of an atom is on, but also indicate whether these electrons are in the same or opposite spin state, while the arrangement of extranuclear electrons does not have the latter function.

In the schematic diagram of atomic structure, we can see that the electrons are arranged in layers outside the nucleus, but there is no indication on which sublayers the electrons are distributed or the spin of each electron. Its advantage is that it can directly see the nuclear charge number of atoms (or the total number of electrons outside the nucleus).

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