The description of the modern periodic table
Modern periodic table
The periods in the modern periodic table
The periods include the elements of the different properties, and they have the same number of energy levels.
By increasing the atomic number for the elements of the period, the atomic size decreases, the electronegativity increases, and the metallic property decreases till we reach the metalloid, then the nonmetallic property increases.
The groups in the modern periodic table
The groups include the elements of similar properties, and they have the same number of electrons in the outermost energy level.
By increasing the atomic number for the elements in the groups, The atomic size increases, the electronegativity decreases, the metallic property increases in the groups which start with the metal, and the nonmetallic property decreases in the groups which start with the nonmetal.
The blocks in the modern periodic table
There are 4 blocks (s, p, d and f). s-block elements are located on the left side of the periodic table and they are arranged in two groups (1 A) and (2 A).
d-block elements are located in the middle of the periodic table, and they are arranged in eight groups (3 B), (4 B), (5 B), (6 B), (7 B), (8), (1 B) and (2 B).
d-block elements are known as the transition elements, They appear to start from the period (4), All the groups in d-block take letter “B” except group (8) which consists of three vertical columns.
The elements of the group (A) are located on the left and the right sides of the table. The elements of groups (B) are located in the middle of the table, and the new number of group (5 A) is (15), while that of zero group is (18).