Definition Of Mendeleev?s Periodic Table

More About Mendeleev’s Periodic Table

• Mendeleev created a periodic table by listing elements in a row in order of atomic weight and starting a new row the characteristics of element began to repeat
• This resulted in arrangement where the element with similar properties occupies the same vertical column
• Mendeleev called these vertical columns as Groups and resultant horizontal rows as Series
• Mendeleev success roots to his vision of classification of elements based on similarities in their empirical formulas and properties of compounds formed by them
• This made him to occasionally ignore the order suggested by atomic weights to classify elements with similar properties together
• For example Iodine with lower atomic weight than Tellurium was placed in Group 7 along with fluorine, chlorine and iodine because of its similarities with their properties
• Mendeleev also left gaps in his periodic table for undiscovered elements
• For example he left gap under aluminum, silicon and Boron in the periodic table for yet to be discovered elements
• Mendeleev not only predicted the existence of these elements and called them Eka-Aluminium, Eka-silicon and Eka-Boron respectively
• Mendeleev also described some of the general physical properties of above elements
• Later these elements discovered and named as Gallium, Germanium and Scandium
• However Mendeleev’s periodic table has certain drawbacks
• Drawbacks of Mendeleev’s Periodic Table:
• - a. Position of element hydrogen is not clear
  - b. There is no place for isotopes of elements in his periodic table
  - c. The placement of element having greater atomic mass before the elements having lower atomic mass could not be logically explained

Solved Example:

Ques: 1. Mendeleev called horizontal rows in periodic table as ____

A. Periods
B. Groups
C. Series
D. Points
Answer A

Solution: Mendeleev called vertical columns in his periodic table as Groups and Horizontal columns as Series in his periodic table