Question

A helium nucleus (also called as $\alpha$ particle) consists of two protons and two neutrons. For a singly ionized helium atom $H{e}^{+},$ the electron's speed in the second orbit (n=2) is___$\times {10}^{6}m/s.$

Answer 1

Using the simplified formula for speed of electron in orbit, and putting Z=2 for helium and n=2 for the second orbit, we get –
$v=\frac{Z}{n}{V}_o$
$\Rightarrow v=\frac{2}{2}{v}_o=v_o=2.19\times {10}^{6}m/s$
That's interesting. The electron in the second orbit of helium ion, $H{e}^{+}$ moves as fast as the electron in the first orbit of hydrogen, H.