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

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.

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 ?

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

How does the chemical reactivity of alkali metals vary on going down 1 of the periodic table?