Which group did iodine belong to in Mendeleev’s table?

Correct option is B

The correct answer is (b) Group VII

Explanation:

• Mendeleev organized elements in his original periodic table primarily based on increasing atomic weight and similar chemical properties.
• Iodine belonged to Group VII because it shared chemical properties with the other elements in that vertical column: Fluorine ($\text{F}$), Chlorine ($\text{Cl}$), and Bromine ($\text{Br}$).
• These elements, known as the halogens, all exhibit similar reactivity, typically forming strong acids with hydrogen (e.g., $\text{HI}$) and salts with metals (e.g., $\text{KI}$).

Information Booster:

• Group VII was also known for containing elements that are generally monovalent (having a valency of 1) in their most common reactions.
• Mendeleev left deliberate gaps in his table for undiscovered elements, showing his confidence in the periodic law.

Additional Knowledge:

• In the modern periodic table, the group that contains the halogens (F, Cl, Br, I) is designated as Group 17.
• Mendeleev's arrangement correctly placed Iodine after Tellurium, despite the slightly higher atomic weight of Tellurium, to maintain the consistency of chemical properties within the groups—a key success of his table.