Question

why is hydrogen called a rogne element in periodic table??

Answer 1

Hydrogen's position is controversial in the periodic table. The properties of hydrogen are different from the other members of its group , the alkali metals do not justify its position in the group , such as its oxide is neutral where as the oxides of alkali metals are basic, alkali metals are most electro positive elements in the table unlike hydrogen, hydrogen forms compounds containing H-ion like halogens where as alkali metals never form negative ions etc, it is the lightest, simplest and most abundant chemical element. that's why , Hydrogen is known as rough element in the periodic table.

Answer 2

Hydrogen is called a rogue element in the periodic table as it exhibits unusual properties, viz. that of alkali metals and those of halogens, hence it could not be placed in any particular group of elements.