Prabin Kalikote

We know,every element of the zero group has achievedstable electronic configuration being duplet stable oroctet stable They have the valencyzero and do not takepart in anychemical reaction. So, elements of thezero group are called inert gas.

We know, alkaline earth metals are foundon the surfaceof the earth in form of oxide which showsproperties similar to that of alkali metals. So, theseelements are called alkaline earth metals.

We know, the properties of f-block elements are similarto the transition metals of d-block, However, theirlast electron enters count f-orbital. So, f-block elementsare kept separately below d-block elements or transitionalelements. Hence, these elements are called innertransitional elements.

We know, the atomic size of fluorine is smaller than that ofchlorine. So, the nuclear attraction is more on the valenceshell of the Fluorine atom. As a result, fluorine can getone electron more easily during the chemical reaction. Hence,fluorine is more reactive than chlorine.

We know, both potassium and sodium are metals andlose the valence electrons. The atomic size of potassiummore than that of sodium. So, the valence electron of potassium canbe moreeasily taken by other reacting atoms ascompared to that of sodium. Hence, potassium is morereactive than sodium.

We know that sodium has positive valency but that of chlorine is negative. The last electron of sodium enters into the s-orbital but that of chlorine enters the p-orbital of the outermost shell. So, sodium is kept in s-block but chlorine is kept in p-block.

a. Mendeleev's and the modern periodic table.