Carbon has an unknown symbol, while potassium's symbol is K. Oxygen's symbol is O and hydrogen's symbol is H. Phosphorus has an unknown extended name provided to help identify it, while lithium's symbol is L. The document recommends reviewing element flash cards online at education.jlab.org/elementflashcards/ or playing element name and symbol games on quizlet.com by searching for user J_albright to help study for an upcoming test.