D Block Elements Flashcards
What are d-block elements?
Elements in which the last electron enters the d-orbital of the
penultimate shell are known as d-block elements
Groups of d-block?
Groups 3-12
How many series of d-block elements?
There are mainly three series of d-block elements, 3d-series (Sc to Zn), 4d-series (Y to Cd), 5d-series , (La to Hg ). The fourth 6d-series which begins with Ac is incomplete.
What is the general electronic configuration of d-block elements?
(n – 1)d1 – 10 ns0 – 2
where (n – 1) stands for penultimate (second last) shell.
Why d-block elements are also known as transition elements?
d-block elements show a transition of properties between s-block
and p-block. Therefore, these are called transition elements.
What is a transition element?
Transition element is an element which has incompletely filled d orbitals in its ground state or in any one of its oxidation
states.
Why Zinc, cadmium, mercury are not regarded as transition metals?
due to completely filled d – orbital.
What are the General Characteristics of transition elements?
i. They are hard metals
ii. They have high melting and boiling points
iii. They show variable oxidation states
iv. Transition metals and their compounds are used as catalysts
v. They form alloys
vi. Form coloured compounds
Why Transition metals have high melting and boiling points?
Transition metals have strong metallic bonds as both ‘ns’ as well as
‘(n-1)d’ electrons take part in bond formation.
Why Transition metals have high enthalpies of atomization?
Transition metals have strong metallic bonds as both ‘ns’ as well as
‘(n-1)d’ electrons take part in bond formation
What is Lanthanoid Contraction? What is the reason for Lanthanoid Contraction?
Lanthanide contraction is the gradual decrease in the atomic and ionic size of
lanthanoids with an increase in atomic number.
Lanthanide contraction is because of filling of 4f orbitals which have poor
shielding effect before the 5d orbitals.
What are the Consequences of Lanthanoid Contraction:
- All the lanthanoids have quite similar properties and due to this
reason they are difficult to separate. - The atomic radii of the second row of transition elements are almost
similar to those of the third row of transition elements.
Why here is slight and irregular variation in ionization energies of transition metals ?
due to irregular variation of atomic size.
- Why the I.E. of 5d transition series is higher than 3d and 4d transition series?
because of Lanthanoid Contraction.
Why Transition metals show variable oxidation states?
due to tendency of (n-1)d as well as ns electrons to take part in bond
formation.
