are there any interesing, less-known facts about the element carbon?
Carbon represents the base of organic chemistry, though graphite (polymorph of element carbon) represents more an element of inorganic chemistry.
Though diamond and graphite are both crystalline forms of carbon (the only two crystalline forms), they do not share the same physical properties regarding hardness. The diamond is the hardest form of carbon, while the graphite represents the softest form.
You know about the presence of carbon dioxide in atmosphere and about the effects of this presence (greenhouse effect), hence it is good for you to know what are the sources that increase the amount of carbon dioxide in atmosphere; they vary from combustion of coal and natural gases to volcanoes' action.
From the pure substance C_60 to the isotope C-14, carbon single or in compounds may have many uses.
Carbonate chemistry is also very present in food industry in different forms, from soft drinks to baking soda or baking powders.