Given alongside is a part of the periodic table : As we move horizontally from left to right :

(i) What happens to the metallic character of the elements ?

(ii) What happens to the atomic size ?

Consider the following elements:

Ca, Cl, Na, I, Li, Ba, Sr, K, Br

Separate these elements into three groups (families) of similar properties. State one property in each on the basis of which you have made your choice.

Mendeleev predicted the existence of certain elements not known at that time and named two them as eka- aluminium, and eka-silicon.

(a) Name the element which has taken the place of (i) eka-aluminium, and (ii) eka-silicon.

(b) Mention the period/periods of these elements in the modern periodic table.

(c) Why is such a classification of elements compared with a characteristic of musical scale ?

(d) State one limitation of this classification of elements.

How would the tendency to gain electrons change on moving from left to right in a period of the periodic table ?

How would the tendency to lose electrons change as we go from left to right across a period of the periodic table?