1 Periodic Table
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What was the need that arose?
To group the elements into families whose elements showed maximum rsemblance.
Early chemists: 1. Basis of arranging 2 Method of arranging 3. Reason for discarding 4. Year
• On the basis of valency, metallic or non-metallic character. • - • Showed Variable Valency and dual character (metalloids). • -
Dobreiner: 1. Basis of arranging 2 Method of arranging 3. Reason for discarding 4. Year
• Atomic weights -> Increasing order • Triads; At. weight of the middle element is average of the other two. • It didnt hold true for all the elements. • 1815
Newland: 1. Basis of arranging 2 Method of arranging 3. Reason for discarding 4. Year
• Atomic weights -> Increasing order • Series of eight; Property of every 8th element is the property of the 1st element. • Didnt leave space for undiscovered elements. • 1864
Medeleef: 1. Basis of arranging 2 Method of arranging 3. Reason for discarding 4. Year
• Atomic weights -> Increasign order. • In a table -> Mendeleef’s periodic table. Properties are periodic funcions of at. weight. • Mehtod couldnt justify -> Certain elements, rare earth and isotopes. • 1869
Mosley: 1. Basis of arranging 2 Method of arranging 3. Reason for Adopting 4. Year
• Increased order of atomic numbers. • In a table -> Modern periodic table. Properties are perioidc functions of atomic number. • Method removes most of the defects of mendeleef. • 1912
Which group in older notation has 3 groups?
VIII -> 8, 9 and 10
In older notation, 18th group is called?
0 group.
Why is atoms arranged in increasing order of atomic number?
Physical and Chemical properties of elements properties of elements of the elements depedns on the number of electrons and their arrangement.
According to which law,modern perioidc table is arranged?
Modern perioidic law -> Physical and Chemical prop. are perioidic functions of their atomic number.
Perioidic table based on the fundamental property ->
Atomic numbers
How does the position of the element corellate?
It correlates with its electronic config.
___ horizontal rows are called ____. ____ vertical columns are called ____.
7, Periods. 18, Groups.
Each period begins and ends with ___ and ___ respectively. Each vertical columns with ____ due to their ____.
Element having 1 electron; 0 Group -> Completely filled. similar prop. ; Aame electronic configuration.
Transition from ___ to ___ is seen across a period.
Metallic to non-metallic
“Across a period” is always
From left to right
What are the normal elemetnts?
1, 2, 3 and 13 to 17 (IA to VIIA)
What are transition elements?
3 to 12 (IB to VIII)
How many group has transition elements?
10 groups
What are the Noble or Inert Gases?
18 (zero)
Where are the following placed in the periodic table? • Reactive metals • Transition elements • Non-Metals
• 1 and 2 • 3 to 12 (middle) • Upper right corner
Name the difference/length of periods:
2, 8, 8, 18, 18, 32
Gradual change in properties is seen with
Increase in atomic number.
Define a period:
Seven horizontal rows of the perioidc table Arranged in inreasing of at. nos