PERIODIC TABLE AND
STRUCTURE
PRESENTED BY
MUHAMMAD AWAIS KHATTAK
TOPIC CONTACT:
 HISTORY OF PERIODIC TABLE?
(1) Al-Razi and Lavoisier:
• Elements are classified into two groups.
a) Metal:
b) Non Metal:
 They arrange 25-30 elements into two groups.
Failure: Failed due to discovery of metalloids.
(2) Doberenier in 1829:
He proposed law of trades
Doberenier arranged elements in a group of three elements.
Atomic mass of middle element can be calculated by taking average of atomic mass of first and third
elements.
Failure
Not applicable for all elements.
(3) Newland in 1884:
He proposed law of octanes.
• Newland arranged elements on the basis of increasing atomic masses
for the first time,
Na ,Mg, Al, Si, P, S ,Cl, Ar
• If elements are arranged on the basis of increasing atomic masses
then every eight element have properties like first element.
Failure:
Due to transition element.
(4) Mendeleev in 1869:
Mendeleev also arranged element on the basis of increasing atomic
masses.
• For the first time, he arranged elements in the form of periodic table.
• Mendeleev is called as father of periodic table.
• Mendeleev periodic table consist of 8 groups and 12 periods.
Physical and chemical properties of elements depend upon atomic
masses.
Advantages:
He left some empty spaces and predicted the discovery of
undiscovered elements.
Disadvantages of Mendeliev:
• He kept different elements in same groups.
• Elements of same properties were kept in different groups.
• He kept Ar before K without specific information which ids against his
statement,
(5) Moseley in 1913:
Henry Moseley arranged elements on the basis of increasing atomic
numbers.
Physical and chemical properties of elements are the periodic function of
their atomic numbers.
He proposed long form of periodic table.
• Periods---7
• Groups(Subgroup A and Subgroup B)
Subgroup A:
Subgroup A is called Normal elements/Typical elements and
representative elements.
Subgroup B:
Transition elements.
According to IUPAC system,there are 18 groups in modern periodic
table
• 1st period contain 2 elements.
• 2nd period contains 8 elements.
• 4th and 5th contain 18 elements.
• 6th period contain 15 elements called lanthanide series.
• 7th period is incomplete and called actinide series.
Limitation of modern periodic table:
• There is no specific place of H atom in periodic table because
hydrogen is non metal and it is keep in metal groups.
• Helium is s block element but kept in p block.
• Metal ,non metal and metalloids are kept in same group.