Compounds are combinations of elements. The combination of those elements is specific to the compound. Some compounds have the exact same elements but in different amounts. Look at C6H12O6, which you hopefully recognize as glucose (think cellular respiration and photosynthesis. But ribose is a 5 carbon sugar and its formula is C5H10O5 which you hopefully recognize (think RNA). They both have the same elements, but have different numbers of each element (sugars all have the 1:2:1 ratio). When you're looking at a formula, it's wise to look for the capital letters. That indicates when a different element is present. For glucose, there's a capital C - carbon, a capital H - hydrogen, and a capital O - oxygen. Behind elements, the subscripts help indicate the number of each element that's present. In glucose, there are 6 carbons, 12 hydrogens, and 6 oxygens. How many carbons, hydrogens, and oxygens does ribose have in its formula?