Identification of group, period &block of elements

Dr Inam Ul Haq Jazbi Identification of Group, Period and Block
Rules for Identification of Group, Period and Block
1. If valence shell electronic configuration of an element is “nsx npy” then element is a representative
element of group A whose:

Block = s or p (i.e. valence or highest energy orbital which contain electron)
Period number = Highest n (i.e. principal quantum number)
Group number = x + y (i.e. total number of valence electrons)
(i) s-block = number of ns electrons
(ii) p-block = no of np electrons + no of ns electron OR
= no of np electrons + 12




Configuration Group Number Period Block
ns1 IA n s
ns2 IIA n s
ns2 np1 IIIA n p
ns2 np2 IVA n p
ns2 np3 VA n p
ns2 np4 VIA n p
ns2 np5 VIIA n p
ns np6 or 1s2
2
VIIIA n p
2. If valence shell electronic configuration of element lies in d-orbital, then element is outer transition
metal belongs to sub-group B. (In transition elements, the outer shell consists of ns and (n–1)d
orbital).

Block = d (i.e. valence or highest energy orbital which contain electron)
Period number = Highest n (i.e. principal quantum number)
Group number = x + y (i.e. total number of valence electrons)
= number of ns Electrons + no of (n-1)d electrons




Configuration Group No. Period Block
(n–1)d1 ns2 IIIB (2+1)/3 n d
(n–1)d2 ns2 IVB (2+2)/4 n d
(n–1)d3 ns2 VB (2+3)/5 n d
(n–1)d5 ns1 VIB (1+5)/6 n d
(n–1)d5 ns2 VIIB (2+5)/7 n d
(n–1)d6 ns2 VIIIB (2+6)/8 n d
(n–1)d7 ns2 VIIIB (2+7)/9 n d
(n–1)d8 ns2 VIIIB (2+8)/10 n d
(n–1)d10 ns1 IB (1+10)/11 n d
(n–1)d10 ns2 IIB (2+10)/12 n d

3. If 4f – orbital is filling, element is Lanthanide of period 6 of f-block. e.g.