Chemistry · General Principles Of Organic Chemistry · NEET
The pointed (narrow) end always touches the carbon in the plane, and the wide (thick) end points toward you, the observer. So a solid wedge starts thin at the central atom and grows thick as it comes out of the paper toward your eyes. Do not flip this, or your 3D shape becomes wrong.
A solid wedge (a filled black triangle) shows a bond projecting out of the plane of paper, toward the observer. A dashed wedge (a series of short parallel lines, drawn like a broken triangle) shows a bond projecting behind the plane of paper, away from the observer. A plain straight line shows a bond lying in the plane of the paper.
A tetrahedral carbon has 4 bonds. Draw two bonds as normal straight lines in the plane of paper, draw one bond as a solid wedge coming toward you, and draw one bond as a dashed wedge going behind. That is 2 in-plane + 1 wedge + 1 dash = the four bonds of an sp3 carbon in 3D.
The dashed wedge simply means the bond goes behind the plane of the paper, away from you. It is not about up or down on the page. NCERT states clearly: solid wedge = out of the plane toward observer, dashed wedge = behind the plane away from observer, normal line = in the plane.
Use wedge-dash to show the shape around a single atom or a small molecule in a simple, visual way. Use a Fischer projection for sugars and chiral centres drawn as a cross, and a Newman projection to view conformations along a C-C bond head-on. Wedge-dash is the most common one asked at NEET level for chirality and 3D structure.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
A solid (filled) wedge means the bond is projecting out of the plane of the paper, toward you the observer. The thin end is at the atom and the thick end points at you.
A dashed (broken) wedge means the bond is projecting behind the plane of the paper, away from you the observer.
A plain straight line means the bond lies in the plane of the paper, neither toward nor away from you.
It is the standard way NCERT draws 3D shapes of molecules, and it is essential for understanding chirality, optical isomerism, and the tetrahedral geometry of carbon, which are directly tested topics.
Usually one solid wedge, one dashed wedge, and two normal lines, giving all four bonds of an sp3 carbon a clear 3D arrangement.
