Mendeleev Periodic Law
Mendeleev explanation that properties of the elements are periodic function of their atomic weights.Modern Periodic Law
Moseley (1913) according to this law physical & chemical properties of the elements are periodic functions of their atomic numbers.
S - Block Elements
Elements of group 1 (Alkali metals) with ns2 outermost electronic configuration.
·
These are all reactive metals with low
ionisation enthalpies.
·
They lose electrons rapidly to form +1
& +2 ions.
·
Metallic character and reactivity
increases on going down the group.
P - Block Elements
These elements belong to group no. 13 to 18.
·
These with s – block elements are called
representative elements.
·
Outermost electronic configuration is
varies from ns2 np1 to ns2 np6.
·
Element of group 18 (ns2 np6)
are known as noble gases or invert gases.
·
Elements of group 17 known as halogens
and elements of group 16 known as chalcogens.
·
Group 16 & 17 elements have high -ve
electron in their outermost shell to attain stable inert gas configuration.
·
Non-metallic character increase on
moving left to right in period and metallic character increases on moving down
in the group.
D - Block Elements
These are elements of group no. 3 to 12 in centres of periodic table. Also known as the transition elements.
·
General outer most electronic
configuration is (n-1)d1-10 n0-2
·
These are all metals
·
Form colours ions and show variable
valences & par magnetism
·
Mainly
used as a catalyst
·
Zn , cd , Hg with configuration (n-1)d10
ns2 do not show most
of the properties of transition elements.
F - Block Elements
These have 2 – rows of elements at bottom of periodic table. i.e. lanthanides Ce (z = 58) to Lu (z = 71) Actinides Th (z = 90) to Lr (z = 103) .
·
Outer electronic configuration =(n-2) f1-14
(n-1) d0-1 ns2.
·
f – block elements also known as inner
transition elements.
No comments:
Post a Comment