Q15 of 59 Page 395

A certain element emits Kα X-ray of energy 3.69 keV. Use the data from the previous problem to identify the element.

Given:


Energy of Kα X-rays= 3.69 KeV or 3690 eV


we’re asked to identify the element which exhibits this behavior,


Wavelength is given by




Using Moseley’s law √c/ = α(Z – b),






Which gives us,



Z=20.17 (atomic number) which can be approximated to Z=20


Therefore, the element with z=20 is calcium (Ca)


More from this chapter

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13

The Kα X-ray of argon has a wavelength of 0.36 nm. The minimum energy needed to ionize an argon atom is 16 eV. Find the energy needed to knock out an electron from the K shell of an argon atom

 14

The Kα X-rays of aluminum (Z = 13) and zinc (Z = 30) have wavelengths 887 pm and 146 pm respectively. Use Moseley’s law √v = α (Z – b) to find the wavelength of the Kα X-ray of iron (Z = 26).

 16

The Kβ X-rays from certain elements are given below. Draw a Moseley-type plot of √v versus Z for Kβ radiation.

 17

Use Moseley’s law with b = 1 to find the frequency of the Kα X-ray of La (Z = 57) if the frequency of the Kα X-ray of Cu (Z = 29) is known to be 1.88 × 1016 Hz.