Compare and contrast the arrangement of elements in Mendeleev’s Periodic Table and the Modern Periodic Table.

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?