Science : Ch 05 – Periodic of Classification of Elements

The element with electronic confguration 2, 8 has octet confguration, so it must be an inert gas, i.e., neon, which is placed in group 18.

As we move from left to right in periodic table, metallic character decreases and non-metallic character increases. Here Na, Si, Cl, Mg, Al belong to same period.

Na and Mg belong to the sameperiod, whereas Na and K are in the same group.In a group from top to bottom, the atomic radius increases, whereas it decreases in a period from left to right. Hence, the order would be K ɳ Na ɳ Mg and K ɳ Ca ɳ Mg

Element  Y  has 1 less electron to complete its octet which is a property of nonmetals. On the other hand, element  Z  has 2 extra electrons to become stable which is a property of metals.

Na and K are alkali metals, whereas Mg and Ca are alkaline earth metals. Alkali metals are more electropositive as compared to alkaline earth metals and can easily lose electrons. Out of Na and K, K will easily lose electrons because of its bigger size and less electronic attraction.

Isotopes have same atomic Isotopes have same atomic number but different number of neutrons; they are the atoms of the same element.

All these elements belong to the same period, in which non-metallic character increases from left to right.   Li, O, C, Be and F belong to the same period, i.e., 2nd period. In a period on moving from left to right, non-metallic character increases.

Non-metals form acidic oxides. The element with atomic number Ǫ is a nonmetal (nitrogen). Rest three elements with atomic numbers.

As we move down in a group, the metallic nature of elements increases.  Be, Mg and Ca are present in the same group (group 2 of the modern periodic table).