Which of the following elements are in this unbalanced chemical reaction: #Li(s) + H_2O(l) -> LiOH(aq) + H_2(g)#?
Each element is represented by one or two letters. If you just want the elements you'll need the symbols.
Look for the capital letters. See if the capital letter is followed by a lower case letter, like with Li. That represents the element lithium.
H is hydrogen, and O is oxygen.
You only need to do one side of the equation because of the law of conservation of matter, both sides of the equations must have the same elements.