Question

what do u mean by the spin angular momentum of the electron - a vector quantity ,can have two oreintations relative to the chosen axis

Answer 1

Dear User,
It was suggested that the electron while moving around the nucleus in an orbit is also spinning about its own axis in clockwise or in anti clockwise direction. There are two possible values either (+1/2) or (-1/2) depending upon the direction of spin. Spinning electron produces angular momentum equal to

${\mu }_{\mathrm{s}}=\sqrt{\mathrm{s}(\mathrm{s}+1)}\frac{\mathrm{h}}{2\mathrm{\pi }}$

This is called spin angular momentum of the electron.