Answer:
The periodic table can be divided into four blocks based on the electron configurations of the elements:
s-block: The elements in the first two groups (Group 1 and 2) have their valence electrons in the s subshell. The maximum number of electrons that can occupy the s subshell is 2.
p-block: The elements in groups 13 through 18 (Group 3 to 8) have their valence electrons in the p subshell. The maximum number of electrons that can occupy the p subshell is 6.
d-block: The elements in groups 3 through 12 (Group 3 to 12) have their valence electrons in the d subshell. The maximum number of electrons that can occupy the d subshell is 10.
f-block: The elements in the two rows at the bottom of the periodic table (the lanthanides and actinides) have their valence electrons in the f subshell. The maximum number of electrons that can occupy the f subshell is 14.
The placement of the elements in the periodic table corresponds to the increasing order of atomic numbers and the arrangement of the subshells they fill. The periodic table is arranged in such a way that elements with similar electron configurations and chemical properties are placed in the same column or group.