Chemistry S & P Block Elements DUHS 2023
PMDC Verified Question 39 of 104
Valence shell electronic configuration of an element is \( 4s^2 \, 4p^1 \). To which group does the element belong?
A
IB
B
IIIB
C
IA
D
IIIA
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: IIIA
Concept:

The group number in the classical A/B system can be determined by the total number of valence electrons. Elements filling s and p subshells belong to the "A" subgroups (Representative elements).

Solution:

  • The given configuration is \( 4s^2 \, 4p^1 \).
  • The highest principal quantum number (\( n=4 \)) tells us it is in the 4th Period.
  • To find the group, sum the electrons in the outermost s and p orbitals:

    $$ 2 (\text{from } 4s) + 1 (\text{from } 4p) = 3 \text{ valence electrons} $$

  • Because the last electron enters a p-orbital, it is a p-block element, categorizing it in the "A" subgroups.
  • With 3 valence electrons, it belongs to Group IIIA (specifically, this is Gallium).


Why other options are incorrect:

  • IB & IIIB: These are transition metals (d-block elements).
  • IA: Would only have an \( ns^1 \) configuration.

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