Periodic table division into blocks

The Periodic Table Elements within the same column of the periodic table have similar outer electron configurations and the same number of valence electrons (electrons in tire outermost principal shell), and tirerefore similar chemical properties. The periodic table is divisible into blocks (s block, p block, d block, and/block) in which particular sublevels are filled. As you move across a period to tire right in tire periodic table, atomic size decreases, ionization energy increases, and metallic character decreases. As you move down a column in the periodic table, atomic size increases, ionization energy decreases, and metallic character increases. 

The filling of the table described above leads to a natural division of the periodic table into blocks according to the outer electron configurations of atoms (see Fig. 2). Elements of the s block all have... 

Fig. 1.13 The modern periodic table in which the elements are arranged in numerical order according to the number of protons (and electrons) they possess. The division into groups places elements with the same number of valence electrons into vertical columns within the table. Under lUPAC recommendations, the groups are labelled from 1 to 18 (Arabic numbers). The vertical groups of three r/-block elements are called triads. Rows in the periodic table are called periods. The first period contains H and He, but the row from Li to Ne is sometimes referred to as the first period. Strictly, the lanthanoids include the 14 elements Ce-Lu, and the actinoids include Th-Lr however, common usage places La with the lanthanoids, and Ac with the actinoids (see Chapter 24).

The long form of the periodic table is divided into four blocks the s-, p-, d- and f-blocks (Chapter 3). This division reflects the filling of the outermost orbitals with electrons (Figure 2.62). 

The periodic table is divisible into four blocks corresponding to the filling of the four quantum sublevels (s, p, d, and f). 

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