Legend Elements in a Molecule 

Add a legend to a 3D model of the molecules in caffeine.

In[1]:=

X caffeine = Show[ChemicalData["Caffeine", "MoleculePlot"], PlotLabel -> Style["Caffeine 3D Molecular Plot", 20], LabelStyle -> {GrayLevel[0.3], Bold}]

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Look up the elements in caffeine and create a legend that matches them with their iconic colors.

In[2]:=

X elements = ChemicalData["Caffeine", "ElementTypes"]; elementLegend = SwatchLegend[ElementData[#, "IconColor"] & /@ elements, elements, LegendMarkerSize -> 20, LabelStyle -> {Bold, GrayLevel[0.3], 18}]

Out[2]=

Add the element legend to the caffeine molecular plot.

In[3]:=

X Legended[caffeine, elementLegend]

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