Question

How many electrons are present in \(_1^2H\),₂He and He⁺? Which of these are hydrogen-like species?

Answer 1

Hydrogen-like species contain only one electron.

Consider \(_1^2H\) :

Number of protons = Number of electrons = 1

Consider ₂He :

Number of protons = Number of electrons = 2

Consider He⁺ :

Number of electrons = (Number of electrons in He – 1) = 2 – 1 = 1

Thus,

\(_1^2H\) and He⁺ are hydrogen-like species. 

[Note : Bohr’s theory is applicable to hydrogen atom and hydrogen-like species, which contain only one electron.]