When a copper salt such as Cu(NO3)2 is burned in a flame, a blue-green color is emitted. Which figure represents the emission spectrum for the element copper? (LO 5.6)? (a)
(b)
(c)
(d)

Verified step by step guidance

1. Understand that the emission spectrum of an element is a set of wavelengths (or colors) of light emitted by atoms of that element when they return to a lower energy state from an excited state.
2. Recognize that the color observed in the flame test (blue-green for copper) is due to the emission of light at specific wavelengths as electrons in the copper atoms fall back to lower energy levels.
3. Identify that the emission spectrum for copper will predominantly show peaks in the regions corresponding to blue and green wavelengths.
4. Compare the provided options (a, b, c, d) and look for the spectrum that shows significant peaks in the blue-green region of the visible spectrum.
5. Select the figure that best matches the description of the emission spectrum with peaks in the blue-green wavelengths, as this will represent the emission spectrum of copper.

Key Concepts

Emission Spectrum

An emission spectrum is a spectrum of the electromagnetic radiation emitted by a source. When an element is heated, its electrons gain energy and can move to higher energy levels. When these electrons return to their original levels, they release energy in the form of light, producing a characteristic spectrum unique to each element.

Copper's Flame Test

Copper salts, such as Cu(NO3)2, produce a distinctive blue-green flame when burned. This color is due to the specific wavelengths of light emitted by excited copper atoms as their electrons transition between energy levels. The flame test is a qualitative analysis technique used to identify the presence of certain metal ions based on the color of the flame.

Energy Levels and Electron Transitions

Atoms have quantized energy levels, and electrons can occupy these levels. When energy is supplied, electrons can jump to higher levels (excitation). The subsequent return to lower levels results in the emission of photons, which correspond to specific wavelengths of light. The pattern of these transitions is what creates the unique emission spectrum for each element.