The elements Be, Mg and Ca each having two electrons in their outermost shells are in periods 2, 3, and 4 respectively of the modern periodic table. Answer the following questions, giving justification in each case (i) Write the group to which these elements belong. (ii) Name the least reactive element. (iii) Name the element having largest atomic radius.
(i) All these elements belong to the 2nd group all have two electrons in their outermost shell. (ii) Be is the least reactive metal because reactivity of metals increases in a period as the tendency to lose electrons in a group increases. Therefore, Be being the smallest in all the given elements of a period has its valance electrons nearest to the nucleus. So the removal of electrons from its valance shell will be difficult. (iii) Ca has the largest atomic radius because it has maximum number of shells, i.e., 4.
