write the magic numbers of periodic table and also write the cause of periodicity in properties of the elements
Answers
If you are referring to magic nos.
Just remember the period to which
they belong and another factor
required will be valence electrons,
generally addition of valence
electrons to magic numbers will
provide its atomic number.
But further when d block elements
come into picture, this shortcut is
applicable only for d block elements
in their respective periods and for
further elements in the same row,
you have to add 10+ valence
electrons.
The magic numbers are 2,8,8,18,18,32
Periodicity in properties
It refers to repetition of similar properties after regular intervals of time when elements are place according to electronic configuration .
Explanation:
MODERN PERIODIC TABLE (Prepared by Bohr)
According to it, properties of elements all periodic function of their atomic numbers.
So, when elements are arranged acc. to increasing atomic no.’s there is periodicity in electronic configuration that leads to periodicity in their chemical properties.
It consist of :
- horizontal rows (Periods)
- Vertical column (Groups)
There are 7 period and 12 groups in this long form of periodic table.
Ist period has 2 elements
IInd period has 8 elements
IIIrd period has 8 elements
IVth period has 18 elements
Vth period has 18 elements
VIth period has 32 elements
VIIth period has rest of elements
These are referred to as magic numbers
please note : The number of valence electron in atom of element decides ,which elements will be first in period and which will be last.
In group:-
- 1 to 2 gp and 13 to 17 contain normal elements
- 3 to 12gp – transition elements.
- 57 to 71 lanthanides
- 89 to 103 Actinides.
Left hand side – metals.
Right hand side – non-metals
Hydrogen element has been placed at top of Ist group. Electronic configuration of H is similar to alkali metal both have 1 valence electron.