Go through the Modern periodic table (fig2.1) and write the names one below the other of the elements of group 1. How many valence electrons are there in each of these elements ?

Go through the Modern periodic table (fig2.1) and write the names one below the other of the elements of group 1. What similarity do you find in their electronic configuration?

By referring to the modern periodic table, find out the group to which the above elements belong.

Mendeleev predicted the existence of certain elements not know at that time. He named two of these elements as eka-aluminium and eka-silicon. a. Name the elements which have taken the place of these elements. b. Mention the group and period of these elements in the modern periodic table. c. Which one of these two elements is a metalloid? d. How many valence electrons are present in eka-silicon? e. Eka-aluminium forms a chloride. What is its formula?

Answer the following questions: How many electrons are there in the outermost shell of group 2 elements?

Answer the following questions: How many electrons are there in the outermost shell of group 18 elements?

On going through the Modern periodic table (fig2.1) it is seen that the elements Li,Be,B,C,N,O,F and Ne belong to the period -2. Write down the electronic configuration.

On going through the Modern periodic table (fig. 2.1) it is seen that the elements Li,Be,B,C,N,O,F and Ne belong to the period - 2. Write down the electronic configuration. Is the number of valence electrons same for all these elements ?

On going through the Modern periodic table (fig. 2.1) it is seen that the elements Li,Be,B,C,N,O,F and Ne belong to the period - 2. Write down the electronic configuration. Is the number of shells the same in these?

How many groups are there in the modern periodic table?

What is the number of valence electrons in an element of group 1 and group 18 respectively?