Absorption And Emission Spectra - The Fingerprints Of Elements
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Absorption And Emission Spectra - The Fingerprints Of Elements

Figure 22.11 illustrates the spectral lines of five elements (A, B, C, D) and a celestial star E.
(a) Identify the elements with the spectral lines of A, B, C and D.
(b) What elements in the star produced the spectral lines of E?
(c) A gaseous substance is more likely to exibit a line spectrum while a liquid or solid is more likely to exhibit a continuous spectrum. Why?

The strings: S7P2A21 (Identity - Physical Properties)

The math:
Pj Problem of Interest is of type identity (physical properties). Spectral lines are unique characteristics of elements and are used to identify elements.

When white light shines on the gaseous form of an atom, the atom absorbs some of the light. The light absorbed shows up as black lines on a rainbow background when examined after it passes through the gaseous form of the element and a prism. This line spectrum is called the absorption spectrum and their wavelengths are the same as those of the emission spectrum which is the result of transitions of electrons from higher energy levels to lower energy levels as they emit their excitation energies.

(a)i A is the line spectrum of the element, hydrogen (H).
(ii) B is the line spectrum of the element, helium (He).
(iii) C is the line spectrum of the element, sodium (Na).
(iv) D is the line spectrum of the element, calcium (Ca).

(b) The celestial star contains hydrogen and helium.

(c) The difference in the nature of the continuity in the spectral lines of gases, liquids and solids is a function of inter-atomic (or inter-molecular) spacing. Gas molecules are farther apart than the molecules of liquids and solids. So, their line spectra indicate transitions of individual atoms. The nearness of the atoms of liquids and to a greater extent solids, allows for group transitions of atoms in addition to the individual transitions of the atoms.

Blessed are they that have not seen, and yet have believed. John 20:29