# About the way chemicals and molecules are represented

The standard way of representing molecules with letters like $\ce{C}$ for Carbon, $\ce{O}$ for Oxygen etc.; and a lot of lines and double lines like a graph from Graph theory where each letter is a 'vertex', the lines like edges. I forget what this chemical notation system is called. Yet it is 2-dimensional. The formula for '$\ce{H2O}$' ,water doesn't indicate the 'angle' of 'separation' between the two Hydrogen atoms that are bonded with the Oxygen atom. Similarly a formula for some molecule like a protein might not indicate all the 'involved angles' in 3-dimensional space that 'allow' it to be folded in a precise way. So does the 2-dimensional notation system for molecules miss details of how a molecule is twisted in 3-D space? Also can two distinct molecules 'look' the same in 2-D notation?

• @user128932, any schematic representation is not going to be fully precise. Molecules can exist in various conformations with disparities that no generic type of projection or formula can encompass down to an arbitrary level of detail. In skeletal formulae, for example, bond angles of tetrahedral atoms are rendered as $120^{\circ}$, making the mental reservation that this is not usually the true angle. However, no two distinct molecules have the same skeletal formulae, as long as the stereochemistry is correctly depicted with wedges/dashes. – Greg E. Sep 1 '14 at 7:23