MHT CET202522 Apr 2025Evening ShiftChemistryClassification of Elements and Periodicity in PropertiesActual
Which is the correct increasing order of atomic radii of Na , K , Mg , Rb ?
Options
- AMg < K < Na < Rb
- BMg < Na < K < Rb
- CMg < Na < Rb < K
- DNa < K < Rb < Mg
Correct answer
B. Mg < Na < K < Rb
Step-by-step solution
Atomic radius is determined by the number of electron shells and effective nuclear charge. Periodic trends: Atomic radius decreases across a period due to increasing nuclear charge while electron shells remain constant. Atomic radius increases down a group as additional electron shells are added, outweighing the shielding effect of inner electrons. The relative positions are: Na (Group 1, Period 3), K (Group 1, Period 4), Mg (Group 2, Period 3), and Rb (Group 1, Period 5). Within Period 3, Mg lies to the right of N