Page 1 - Microsoft Word - Lesson note-1(d-block element )

SUBJECT-CHEMISTRY

CHAPTER-D-BLOCK ELEMENT

SUBTOPIC- Electronic configuration,atomic and ionic radii,ionization
enthalpies,enthalpy of atomization, oxidation state, standard
reduction potential.

KEY NOTES:

 Transition elements: The elements lying in the middle of
periodic table belonging to group 3 to 12 are known as d-

block elements.
 All the transition elements exhibit typical metallic

properties such as-high tensile strength, ductility,

malleability, thermal and electrical conductivity and
metallic character.

 The atomic radii decrease from Sc to Cr because number
of unpaired electrons increases. The atomic size of Fe,

CO, Ni is alomat same, because pairing of electrons
takes place. The increase for Cu and Zn.

 The elements which give the greatest number of oxidation

states occur in or near the middle of the series. Manganese, for
example, exhibits all the oxidation states from +2 to +7. The
lesser number of oxidation states at the extreme ends stems

from either too few electrons to lose or share (Sc, Ti) or too
many d electrons (hence fewer orbitals available in which to
share electrons with others) for higher valence (Cu, Zn).

 The amount of energy required to separate the metal atom
from its crystal is called enthalpy of atomization.
 Standard reduction potential depends on ionisation

enthalpy,sublimation enthalpy and enthalpy of
atomisation.