2. structure of atom — Chemistry STD 11 Science — Question

Radius of $H$ atom $r _{ H }=0.529 \,\mathring A$

For $He ^{+}$ion: $n=2, Z=2$

$r _{ He ^{+}}=0.529\left[\frac{2^2}{2}\right]=2 r _{ H }$

For $Li ^{2+}$ ion: $n =2, Z =3$

$r_{L^{i i^2}}=0.529\left[\frac{2^2}{3}\right]=\frac{4}{3^{r_H}}$

For $Li ^{2+}$ ion: $n =3, Z =3$

$r_{L_{i^{2+}}}=0.529\left[\frac{3^2}{3}\right]=3 r_H$

For $Be ^{3+}$ ion: $n=2, Z=4$

$r_{ Be ^{3+}}=0.529\left[\frac{2^2}{4}\right]=r_H$

$Be ^{3+}(n=2)$ has the same radius as that of the $1^{\text {st }}$ Bohr's orbit of hydrogen atom.