Ключевые слова: atom, atomic, background, biology, black, blackboard, board, bond, caffeine, chalk, chalkboard, chemical, chemistry, class, coffee, composition, compound, concept, drawing, drug, element, formula, handwriting, health, illustration, medical, medicine, model, molecular, molecule, organic, research, school, science, scientific, sign, stimulant, stimulate, structural, structure, substance, supplement, symbol, technology, text, texture, white, word, write,