For the H2CO3Lewis structure (Carbonic Acid) make sure you put the Hydrogen atoms on the outside of the oxygen atoms. Lewis structure of H2CO3? 2008-09-09 19:28:42 2008-09-09 19:28:42. Related Questions. Explanation : Lewis-dot structure : It shows the bonding between the atoms of a molecule. With H2CO3, Carbon (C) is the least electronegative and goes in the center of the structure. The first thing we do is count the valence electrons. When we are determining the shape of a molecule then it is important to draw a Lewis-dot structure and for drawing a Lewis-dot structure we should know that how many total number of valance electrons present in a given compound or a molecule. Wiki User. Originally Answered: What is the Lewis dot structure for H2CO3? See the Big List of Lewis Structures There are a total of 24 valence electrons in H2CO3. Answer : The shape of is, trigonal planar.. Top Answer. Now that we have the number of valence electrons we identify the central atom which is C. Important part here also is that H … H - O - C - O - H-----O There are 4 dots on each of the oxygens. H (1), C (4), O (6), if we sum it up we get 2*1+4+3*6=24.