The Lanthanoids
Chapter Name : The D- And F- Block Elements |
Sub Topic Code : 102_12_08_05_02 |
Topic Name : The Lanthanoids |
|
Sub Topic Name : Atomic And Ionic Sizes |
|
Introduction
• The overall decrease
in atomic and ionic radii from lanthanum to lutetium (the lanthanoid
contraction) is a unique feature in the chemistry of the lanthanoids
•
The decrease in atomic radii is not quite regular as
it is regular in M3+ ions
•
This contraction is similar to that observed in an
ordinary transition series and is due the imperfect shielding of one electron
by another in the same sub-shell.
•
However, the shielding of one 4 f electron by another
is less than one d electron by another
•
There is fairly regular decrease in the sizes with
increasing atomic number.
•
The cumulative effect of the lanthanoid contraction,
causes the radii of the members of the third transition series to be very
similar to those of the corresponding members of the second series.
Pre-Requisites:
Periodic table, elements
Activity:
Sunglass lenses have lanthanoide coating which deflects UV
Real Life Question:
null
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| group | Group is the vertical column on the periodic table which contains elements having the similar properties |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Sunglass lenses | Sunglass lenses have lanthanoide coating which deflects UV |
Real life uses :
Sunglass lenses use lanthanides for
deflecting UV and IR radiation
Places to visit :
Optical shop
Practical examples around us
| Examples | Explainations |
|---|---|
| Sunglass lenses | Sunglass lenses use lanthanides for deflecting UV and IR radiation |
What you learn in Theory:
• The overall decrease
in atomic and ionic radii from lanthanum to lutetium (the lanthanoid
contraction) is a unique feature in the chemistry of the lanthanoids
•
The decrease in atomic radii is not quite regular as
it is regular in M3+ ions
•
This contraction is similar to that observed in an
ordinary transition series and is due the imperfect shielding of one electron
by another in the same sub-shell.
•
However, the shielding of one 4 f electron by another
is less than one d electron by another
•
There is fairly regular decrease in the sizes with
increasing atomic number.
The cumulative effect
of the lanthanoid contraction, causes the radii of the members of the third
transition series to be very similar to those of the corresponding members of
the second series.
What you learn in Practice:
• The overall decrease
in atomic and ionic radii from lanthanum to lutetium (the lanthanoid
contraction) is a unique feature in the chemistry of the lanthanoids
•
The decrease in atomic radii is not quite regular as
it is regular in M3+ ions
•
This contraction is similar to that observed in an
ordinary transition series and is due the imperfect shielding of one electron
by another in the same sub-shell.
•
However, the shielding of one 4 f electron by another
is less than one d electron by another
•
There is fairly regular decrease in the sizes with
increasing atomic number.
The cumulative effect
of the lanthanoid contraction, causes the radii of the members of the third
transition series to be very similar to those of the corresponding members of
the second series.