MOSELEY'S EXPERIMENT - PERIODIC LAW

Henry Moseley has conducted one experiment wherein inside a discharged tube the cathode rays were made to fall on a metal target like Tungsten (W) also called as Anti cathode. Observation: Moseley has observed that a new type of electromagnetic radiations (EMRs) was deflected at 45-degree angle, which were nothing but X – rays. Frequency (ν) of deflection of X rays varied when the target metal. From the experimental observations, Moseley has noticed that the square root of frequency is directly proportional to the atomic number of the target metal √ ν (Frequency of x rays α Z (atomic no) – Moseley’s Law √ ν = a (Z-b) – Moseley’s equation; ν – Frequency of emitted X rays; Z – Atomic number Applications: Moseley Periodic Law helped in i) arranging various elements in the periodic table in the order of increasing atomic Number. ii) Useful in calculation of frequency of different X-ray spectral lines such as Kα, Kb etc., iii) X-ray spectroscopy in physics using Bragg's diffraction law, helped in determination of internal atomic & molecular structure of crystalline solids iv) Moseley work led to discovery of unknown metals like Technetium (43), Hafnium (72), and Rhenium (75) in periodic table