Ключевые слова: 13, al, aluminum, atom, atomic, atomic mass, atomic number, atoms, chemical, chemical symbol, chemistry, concept, drawing, electron, element, elements, formula, hand, illustration, laboratory, lightweight, mass, metal, molecule, molecules, nuclear, number, pen, periodic, periodic table, periodic table of elements, proton, pse, research, science, scientific, scientist, sign, structure, substance, symbol, table, technology, text, whiteboard, write, writing,