Class 11 NEET Chemistry Classification Of Elements And Periodicity In Properties

Concept:Metallic character decreases from left to right across a period and increases from top to bottom in a group.Chemical Equation / Formula:Electronegativity and metallic character are inversely related:$\text{Electronegativity} \propto \frac{1}{\text{Metallic character}}$Explanation:Compare the positions of the given elements in the periodic table.$\mathrm{Na}$ and $\mathrm{Mg}$ are in period 3; $\mathrm{Na}$ is to the left of $\mathrm{Mg}$, so $\mathrm{Na}$ is more metallic.$\mathrm{Be}$ is in period 2, group 2; it is above $\mathrm{Mg}$, so $\mathrm{Be}$ is less metallic than $\mathrm{Mg}$.$\mathrm{Si}$ and $\mathrm{P}$ are in period 3; $\mathrm{Si}$ is to the left of $\mathrm{P}$, so $\mathrm{Si}$ is more metallic than $\mathrm{P}$.Also, $\mathrm{Be}$ (period 2) is above $\mathrm{Si}$ (period 3) in group 14? No, $\mathrm{Be}$ is group 2, $\mathrm{Si}$ is group 14 — but comparing across periods, $\mathrm{Be}$ is more metallic than $\mathrm{Si}$.The order of increasing metallic character (least metallic first) is:$\mathrm{P} < \mathrm{Si} < \mathrm{Be} < \mathrm{Mg} < \mathrm{Na}$Check with electronegativity values (Pauling scale): $\mathrm{Na}\,0.9$, $\mathrm{Mg}\,1.2$, $\mathrm{Be}\,1.5$, $\mathrm{Si}\,1.8$, $\mathrm{P}\,2.1$.Higher electronegativity means lower metallic character.This matches the order above.Answer:Option A: $\mathrm{P} < \mathrm{Si} < \mathrm{Be} < \mathrm{Mg} < \mathrm{Na}$