Question

Imagine removing one electron from $H{e}^4$ and $H{e}^3$. Their energy levels, as worked out on the basis of Bohr model will be very close. Explain why.

Answer 1

Bohr model is applicable for hydrogen atom-and some lighter atoms in which a single electron revolves around a stationary nucleus of positive charge $Ze$ (called hydrogen like atom). If we remove one electron from the isotopes of $H{e}^4$ and $H{e}^3$, the energy levels will be very close as both the nuclei are very heavy as compared to electron mass. Also, after removing one electron from $H{e}^4$ and $H{e}^3$ atoms will have one electron as in hydrogen atoms, and the nucleus is much heavier than $H$ atom.

$\text{Final Answer}:$ Because both the nuclei are very heavy as compared to electron mass.