Question

Consider an atom traveling at 3% of the speed of light. The de Broglie wavelength is found to be 1.42x10^-3 pm. Which element is this?

a) He

b) P

c) F

d) Be

e) Ca

Answer 1

    = h/mv

v   = 3% of the speed of light = 0.03*3*10^10cm/sec   = 9*10^8cm/sec

    = 1.42*10^-3 Pm = 1.42*10^-3 *10^-10cm = 1.42*10^-13 cm

h   = 6.625*10^-27 erg-sec

m = h/V

    = 6.625*10^-27/9*10^8*1.42*10^-13    = 5.18*10^-23g

avogadro' number = 6.023*10^23/mole

atomic mass of element   = 5.18*10^-23 *6.023*10^23   = 31.2g/mole >>>>>P

The element is P

b) P>>>>>answer