The atomic number of hydrogen is 1 and that of helium is 2. Why is hydrogen(a non-metal) placed in the first group and helium in the 18th group?
The atomic number of hydrogen is 1 and that of helium is 2. Why is hydrogen(a non-metal) placed in the first group and helium in the 18th group?
The correct option is B Both hydrogen and alkali metals have a single valence electron
The first group of the periodic table consists of alkali metals like Lithium, Sodium, Potassium, Rubidium, Caesium and Francium. All these elements have only one valance electron just like hydrogen. Due to this similar property of forming M+ or H+ ion(for alkali metals and hydrogen respectively), hydrogen is placed in the first group of the periodic table.
Helium has a noble gas configuration like that of the group 18 elements i.e., Neon, Argon, Krypton, Xenon, and Radon. They don't react with other elements due to their stable electronic configuration. Thus, Helium belongs to group 18 in the periodic table.
Both hydrogen and alkali metals have a single valence electron
The first group of the periodic table consists of alkali metals like Lithium, Sodium, Potassium, Rubidium, Caesium and Francium. All these elements have only one valance electron just like hydrogen. Due to this similar property of forming M+ or H+ ion(for alkali metals and hydrogen respectively), hydrogen is placed in the first group of the periodic table.
Helium has a noble gas configuration like that of the group 18 elements i.e., Neon, Argon, Krypton, Xenon, and Radon. They don't react with other elements due to their stable electronic configuration. Thus, Helium belongs to group 18 in the periodic table.
