A block of the periodic table of elements is a set of adjacent groups. The term appears to have been first used (in French) by Charles Janet. The respective highest-energy electrons in each element in a block belong to the same atomic orbital type. Each block is named after its characteristic orbital; thus, the blocks are:

The block names (s, p, d, f and g) are derived from the quality of the spectroscopic lines of the associated atomic orbitals: sharp, principal, diffuse and fundamental, the rest being named in alphabetical order, omitting j.) Blocks are sometimes called families.

The following is the order for filling the "subshell" orbitals, according to the Aufbau principle, which also gives the linear order of the "blocks" (as atomic number increases) in the periodic table:

For discussion of the nature of why the energies of the blocks naturally appear in this order in complex atoms, see atomic orbital and electron configuration.

The "periodic" nature of the filling of orbitals, as well as emergence of the s, p, d and f "blocks" is more obvious, if this order of filling is given in matrix form, with increasing principal quantum numbers starting the new rows ("periods") in the matrix. Then, each subshell (composed of the first two quantum numbers) is repeated as many times as required for each pair of electrons it may contain. The result is a compressed periodic table, with each entry representing two successive elements:

Block may refer to:

The periodic table is a tabular display of the chemical elements, organized on the basis of their properties. Elements are presented in increasing atomic number. The main body of the table is a 18 × 7 grid, with gaps included in to keep elements with similar properties together, such as the halogens and the noble gases. These gaps form four distinct rectangular areas or blocks. The f-block is not included in the main table, but rather is usually floated below, as an inline f-block would make the table impractically wide. The periodic table accurately predicts the properties of various elements and the relations between properties. As a result, it provides a useful framework for analyzing chemical behavior, and is widely used in chemistry and other sciences.

Although precursors exist, the current table is generally credited to Dmitri Mendeleev, who developed it in 1869 to illustrate periodic trends in the properties of the then-known elements; the layout has been refined and extended as new elements have been discovered and new theoretical models developed to explain chemical behavior. Mendeleev's presentation also predicted some properties of then-unknown elements expected to fill gaps in his arrangement; these predictions were proved correct when those elements were discovered and found to have properties close to the predictions.

Table or Tables may refer to:

Song In (in hangul 송인, in hanja 宋仁) was a civil official in the mid-Goryeo era who became the intermediary founder of the Jincheon Song clan. His highest post was munha pyeongjangsa (문하 평장사). This was the highest government position in the period. Song In was responsible for administration, judicial affairs and economy in the district.

As he performed meritorious deeds during the King, he was conferred with Chanhwagongsin and Jincheonbaek. Baek was a position of politicians who were responsible for administration, judicial affairs and economy in the district. As the government created him Jincheonbaek, his family started regarding Jincheon as their origin. Hence, the family origin became Jincheon Song.

When he was in the position of Sangsanbaek, he tried to be just and fair in all the administrative affairs and strived to enhance the welfare of his people. He also focused on education for the youth and courtesy for people, which made his district famous for most excellent behaviors in the nation. After that, the people have long paid tribute to his feats.