| Mendeleev’s Periodic Table | Modern Periodic Table |
| Elements are arranged in the increasing order of their atomic masses | Elements are arranged in the increasing order of their atomic numbers. |
| There are 8 groups | There are 18 groups |
| Each group is subdivided into subgroup 'a' and 'b' | Groups are not subdivided into subgroups. |
| Groups for Noble gas was not present as noble gases were not discovered by that time | A separate group is meant for noble gases. |
| There was no place for isotopes. | This problem has been rectified as slots are determined according to atomic number. |
Answered by Shivani Kumari | 2 years ago
In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium?
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
The position of three elements A, B, and C in the Periodic Table are shown below– Group 16 Group 17 - - - A - - B C
(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B?
(d) Which type of ion, cation or anion, will be formed by element A?
An atom has electronic configurations 2, 8, 7.
(a) What is the atomic number of this element?
(b) To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.) N(7), F(9), P(15), Ar(18)