The description of the modern periodic table
Modern periodic table
The modern periodic table consists of 7 horizontal periods and 16 vertical groups ( 18 vertical columns ) . The elements of the modern periodic table are classified into 4 blocks ( s , p , d and f ) .
The periods in the modern periodic table
The periods includes the elements of the different properties , And they have the same number of the 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 includes the elements of the similar properties , and they have the same number of the 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 ) .
p-block elements are located on the right side of the periodic table , and they are arranged in six groups ( 3 A ) , ( 4 A ) , ( 5 A ) , ( 6 A ) , ( 7 A ) and zero group .
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 period ( 4 ) , All the groups in d-block take letter ” B ” except group ( 8 ) which consists of three vertical columns .
f-block elements are located below the periodic table , They include lanthanides and actinides .
The elements of 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 ) .