Question

Certain elements emit light of a specific wavelength when they are burned. Historically, chemists used such emission wavelengths to determine whether specific elements were present in a sample. Some characteristic wavelengths for some of the elements are:
Ag= 328.1 nm Fe= 372.0 nm
Au= 267.6 nm K= 404.7 nm
Ba=455.4 nm Mg= 285.2 nm
Ca= 422.7 nm Na= 589.6 nm
Cu= 324.8 nm Ni= 341.5 nm

Part A: Determine which elements emit radiation in the visible part of the spectrum.
Check all that apply.

{Ag}
{Au}
{Ba}
{Ca}
{Cu}
{Fe}
{K}
{Mg}
{Na}
{Ni}

Part B: Which element emits photons of highest energy?

{Ag}
{Au}
{Ba}
{Ca}
{Cu}
{Fe}
{K}
{Mg}
{Na}
{Ni}

Part C: Which element emits photons of lowest energy?

{Ag}
{Au}
{Ba}
{Ca}
{Cu}
{Fe}
{K}
{Mg}
{Na}
{Ni}

Part D: When burned, a sample of an unknown substance is found to emit light of frequency uploaded image Which of these elements is probably in the sample?

{Ag}
{Au}
{Ba}
{Ca}
{Cu}
{Fe}
{K}
{Mg}
{Na}

Answer 1

Answer:

A. {K}, {Ba}, {Ca}, {Na}

B. {Au}

C. {Na}

D. Image Missing

Explanation:

PART A:

The range of  wavelengths in visible region is 380 nm to 740 nm. Thus, all the elements that emit light of wavelength in this region are the elements which emit radiation in visible part. They are:

{k}

{Ba}

{Ca}

{Na}

PART B:

The energy of a photon is inversely proportional to its wavelength (E = hc/λ). Therefore, the element, which emits the radiation of smallest wavelength, has the highest energy photons. That element is {Au}

PART C:

Similarly, the element which emits radiation of highest wavelength, has the lowest energy. That element is {Na}

PART D:

Image missing.