How can I know how many hydrogens are there for each Carbon in bond line notations?
Line notation implies that you should well-know the octet rule and can mentally interconvert between full structures and line notations. Just mentally add a hydrogen until the central carbon has an octet (or 4 single bonds, two single bonds and one double bond, two double bonds, or one single and one triple bond).
i.e. propane is
The number of hydrogens is
- The carbon atoms and the hydrogen atoms attached to them are not shown.
- Only the bonds between the carbon atoms are shown as lines.
- The vertices and end of lines represent the carbon atoms.
- Any unfilled valences on carbon are assumed to be filled by hydrogen atoms.
- All atoms other than carbon, plus any hydrogen atoms attached to them, are shown.
For example, the bond line notation for propane is
In the above diagram, the vertex and the ends of the lines represent the carbon atoms.
The two end
In the above molecule, the three
The ring carbon that is attached to the side chain has 3 bonds, so it has one
The remaining four carbons each have two bonds, so they have two