Question

In Mendeleev's periodic table, the groups were divided into how many subgroups?

Answer 1

Mendeleev's Periodic Table:

• In Mendeleev's periodic table the elements were arranged on the basis of their fundamental property, the atomic mass, and also on the similarity of chemical properties.
• There were $63$ elements known at the time of Mendeleev's periodic table.
• $63$ elements were arranged in the increasing order of their atomic masses and found that the elements with similar chemical properties occur at regular intervals.
• Mendeleev's periodic law states that “the properties of elements are a periodic function of their atomic masses”.

Number of groups:

• Mendeleev observed that elements with similar properties fall in the same vertical column.
• These vertical columns are called groups and horizontal rows of elements are called periods.
• There are eight groups present in Mendeleev's periodic table.
• Groups from $\left(\mathrm{I}-\mathrm{VII}\right)$ are meant for normal elements and group $\mathrm{VIII}$ is for transition elements.
• Groups from $\left(\mathrm{I}-\mathrm{VII}\right)$ have been divided into two subgroups, while group $\mathrm{VIII}$ is meant for three elements.
• These subgroups were designated as $\mathrm{A}$ and $\mathrm{B}$ as shown below:

Hence, in Mendeleev's periodic table, the groups were divided into two subgroups.