What are groups and periods. Write some features of groups and periods of modern periodic table

What are groups and periods. Write some features of groups and periods

1.	What are groups and periods. Write some features of groups and periods of modern periodic table
Answer» The long form of periodic table consist of vertical columns called groups and horizontal rows called periods.Salient feature of the Modren periodic table are: 1. the periodic table has 18 vertical columns called groups. and seven horizontal rows called periods. 2. The elements of group 1,2, 13, 14, 15 , 16 and 17 are known as the main group or representative elements. 3.The elements of group 3,4,5,6,7,8,9, 10 ,11 and 12 are known as transition elements 4. Element 18 are called noble gases or inert gases. 5.The first period contains only 2 elements and is the shortest period. 6. The second and third period contain 8 elements and is called short period. 7. The fourth and fifth period contains 18 elements. these are long periods. 8. The sixth period contain 32 elements . it is longest period. 9. The seventh period is incomplete. 10. in group 3 of sixth period there is set of elements with atomic number 57 to 71 . they are known as lanthanides. 11. In group 3 of seventh period the elements with atomic number 89 -103 are known as actinides.