Which one of the following statement is correct about Mendeleev’s periodic table of elements?
Right Answer is:
It has the elements arranged in order of their increasing atomic numbers
Mendeleev’s Periodic Table
According to Mendeleev, the properties of elements were related to their atomic weights. On this basis, he formulated his periodic law. Mendeleev’s periodic law states that the physical and chemical properties of the elements are the periodic functions of their atomic weights. Therefore, the elements have been arranged in the increasing order of their atomic weights. He compiled a periodic table by arranging the 63 elements known then in eight vertical columns called groups and seven horizontal rows known as periods. Later, when the noble gases were discovered, Mendeleev gave a modified periodic table by including the noble gases in zero groups. He categorized the table into eight (columns) groups and seven periods (rows). The groups range from zero to eight and these except the zero and the eighth group was further subdivided into two subgroups A and B. He numbered the periods from 1 to 7 of which the seventh period is incomplete.
Merits of Mendeleev’s Periodic Cable
- Mendeleev left some gaps for some undiscovered elements in the periodic table. The properties of these elements could be predicted based on the properties of other elements present in the same group. He named these missing elements as Eka boron, Eka aluminum and Eka silicon that were later discovered and named as scandium, gallium, and germanium, respectively.
- Mendeleev corrected the doubtful atomic weights of some elements like indium, beryllium, and uranium.
- One of the strengths of Mendeleev’s periodic table was that when inert gases were discovered they could be placed in a new group without disturbing the existing order.