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Structure Of Atom

Question
CBSEENCH11005358

Indicate the number of unpaired electrons in:
(a) P, (b) Si, (c) Cr, (d) Fe and (c) Kr. 

Solution
space left parenthesis straight a right parenthesis space straight P presubscript 15 colon space space 1 straight s squared space 2 straight s squared space 2 straight p to the power of 6 space 3 straight s squared space 3 straight p subscript straight x superscript 1 space 3 straight p subscript straight y superscript 1 space 3 straight p subscript straight z superscript 1
space Number space of space unpaired space of space electron space equals 3
space space left parenthesis straight b right parenthesis space Si presubscript 14 colon space 1 straight s squared 2 straight s squared 2 straight p to the power of 6 3 straight s squared 3 straight p subscript straight x superscript 1 3 straight p subscript straight y superscript 1
Number space of space unpaired space electrons space equals 2

space left parenthesis straight c right parenthesis space Cr presubscript 24 colon space space 1 straight s squared 2 straight s squared 2 straight p to the power of 6 3 straight s squared 3 straight p to the power of 6 4 straight s to the power of 1 3 straight d to the power of 5
Number space of space unpaired space electrons space equals space 6

space space left parenthesis straight d right parenthesis space Fe presubscript 26 colon space 1 straight s squared 2 straight s squared 2 straight p to the power of 6 3 straight s squared 3 straight p to the power of 6 4 straight s squared 3 straight d to the power of 6
Number space of space unpaired space electrons space equals space 4

space left parenthesis straight e right parenthesis space Kr presubscript 36 colon space 1 straight s squared 2 straight s squared 2 straight p to the power of 6 3 straight s squared 3 straight p to the power of 6 4 straight s squared 3 straight d to the power of 10 4 straight p to the power of 6
Number space of space unpaired space electrons space equals 0