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SUBJECT-CHEMISTRY

CHAPTER-Periodic classification of element

SUBTOPIC- Modern periodic table and IUPAC nomenclature of the elements.

KEY NOTES :

MODERN PERIODIC CLASSIFICATION:

 This classification was done by Henry Moseley in 1911.
 Modern Periodic Law

The physical and chemical properties of elements are periodic function of
their atomic numbers.

i.e. the elements are arranged in increasing order of their atomic numbers.
Important features of modern periodic table:

 This table consists of 7 horizontal rows called periods, 18 vertical
columns called groups and 4 blocks.
 Periods: The horizontal rows from left to right are called periods.

There are 7 periods.
st
 1 period has 2 elements.(H & He)
nd
 2 period has 8 elements.(Li - Ne)
rd
 3 period has 8 elements.(Na - Ar)
th
 4 period has 18 elements.(K - Kr)
th
 5 period has 18 elements.(Rb - Xe)
th
 6 period has 32 elements.(Cs - Rn)
th
 7 period has 32 elements &
incomplete.(Fr - Uuo)

 Groups: The vertical columns from top to bottom are called groups.

 There are 18 groups present in the periodic table.
 Group 1- Alkali metals.

 Group 2 – Alkaline earth metals.
 Group 11 – Coinage metals

 Group 15 – Pnicogens
 Group 16 – Chalcogens

 Group 17 – Halogens