In which of the following systems will the radius of the first orbit $(n=1)$ be minimum?

In which of the following systems will the radius of the first orbit $(n=1)$ be minimum?
  1. Doubly ionized lithium
  2. Singly ionized helium
  3. Deuterium atom
  4. Hydrogen atom

Solution

Radius of the first orbit of an atom \(R_1=\frac{0.529}{Z} A^{\circ}\)
\(\Rightarrow \mathrm{R}_1 \propto \frac{1}{\mathrm{Z}}\)
where \(Z\) is the atomic number of Hydrogen-like atom.
Since \(Z\) is maximum for doubly ionized lithium, thus radius of first orbit is minimum in doubly ionized lithium.

Asked in: NEET 2003

Practice more Structure of Atoms and Nuclei questions on Aicharya