Compare and contrast the arrangement of elements in Mendeleev's periodic table and the Modem periodic table.

Four elements A,B,C, and D have atomic numbers 12, 13, 14 and 15 respectively.

Answer the following questions giving reasons:

a. What is the number of valence electrons and valency of D?

b. Which of them will have largest atomic radii?

C. which of these elements will form the most basic oxide?

Write the number of periods and groups in the Modern Periodic Table. How does the metallic character of elements vary on moving (i) from left to right in a period, and (ii) down a group? Give reason to justify your answer.

In the modem 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 ?

Name:

(a) three elements that have a single electron in their outermost shells.

(b) two elements that have two electrons in their outermost shells.

(c) three elements with filled outermost shells.