Ключевые слова: alkane, atom, atomic, black, blue, carbon, chemical, chemistry, composition, compound, design, drawing, drawn, education, element, flat, formula, geometric, graphic, hydrocarbon, hydrogen, icon, illustration, isolated, laboratory, line, model, molecular, molecule, natural, organic, outline, pictogram, propane, research, school, science, scientific, sign, skeletal, structure, substance, symbol, white,