Carbon Structures without end

The single bonds mark a three-dimensional tetrahedral structure: four electron densities ("balloons") around carbon.

The structure of a double bond is two-dimensional planar trigonal: three electron densities (one of them double) around each carbon.

The atoms involved in a triple bond form a one-dimensional linear structure: two electron densities (two of them triple) around each carbon.

The single bonds mark a three-dimensional tetrahedral structure: four electron densities ("balloons") around carbon. Oxygen has four electron densities too (not shown) and they are in tetrahedral arrangement. However, oxygen sustains two bonds that end up in angular disposition.

The single bonds mark a three-dimensional tetrahedral structure: four electron densities ("balloons") around carbon. Nitrogen has four electron densities too (not shown) and they are in tetrahedral arrangement. However, nitrogen sustains three bonds that end up in pyramidal disposition.

The single bonds mark a three-dimensional tetrahedral structure: four electron densities ("balloons") around carbon. Sulphur has four electron densities too (not shown) and they are in tetrahedral arrangement. However, sulphur sustains two bonds that end up in angular disposition.

The four single bonds around the methyl carbons mark a three-dimensional tetrahedral structure: four electron densities ("balloons") around carbon. However, the carbonyl carbon only bears three electron densities (one double) and ends up as trigonal planar.

All pyridine carbons and nitrogen bear three electronic densities (the unshared electron pair of N is not shown). Therefore, all carbons are trigonal planar. The C–N–C bonds of nitrogen end up angular.

The four single bonds around the methyl carbon mark a three-dimensional tetrahedral structure. The atoms involved in a triple bond form a one-dimensional linear structure: two electron densities (one of them triple) around each carbon.