A wedge and dash projection is a drawing, a means of representing a molecule in which three types of lines are used in order to represent the three-dimensional structure: Dashed lines to represent bonds that extend away from the viewer. Wedge-shaped lines to represent bonds oriented facing the viewer.

Water has 4 regions of electron density around the central oxygen atom (2 bonds and 2 lone pairs). These are arranged in a tetrahedral shape. The resulting molecular shape is bent with an H-O-H angle of 104.5°.

104.50
The bond angle in H2O is 104.50.

Water is a simple molecule consisting of one oxygen atom bonded to two different hydrogen atoms. Because of the higher electronegativity of the oxygen atom, the bonds are polar covalent (polar bonds). The molecule adopts a bent structure because of the two lone pairs of electrons on the oxygen atom. …

VSEPR calculation for water, OH. Water has four electron pairs and the coordination geometry of oxygen is based upon a tetrahedral arrangement of electron pairs. Since there are only two bonded groups, there are two lone pairs. Since the lone pairs are not ‘seen’, the shape of water is bent.

Some examples of wedges that are used for separating might be a shovel, a knife, an axe, a pick axe, a saw, a needle, scissors, or an ice pick. But wedges can also hold things together as in the case of a staple, push pins, tack, nail, doorstop, or a shim.

An example of bent molecular geometry that results from tetrahedral electron pair geometry is H2O. The water molecule is so common that it is wise to just memorize that water is a BENT molecule. The oxygen has 6 valence electrons and thus needs 2 more electrons from 2 hydrogen atoms to complete its octet.

Wedge formula: An equation relating the volume of liquid material in a ship’s tank to the dip, ship’s trim, dipping point location and the tank’s dimensions when the ship’s calibration tables cannot be applied. The wedge formula is to be used only when the liquid does not touch all bulk heads of the vessel’s tanks.

The water molecule is bent molecular geometry because the lone electron pairs, although still exerting influence on the shape, are invisible when looking at molecular geometry.

They are rarely needed for sp2(e.g. alkenes) or sp systems (e.g. alkynes). Wedge-hash diagrams are usually drawn with two bonds in the plane of the page, one infront of the plane, and one behind the plane. This gives the molecule 3D perspective: we envisage the bold lines being closer to us and the hashes fading away in the background.

In order to determine the molecular geometry for H2O, observe the Lewis structure of the same. There is an atom of oxygen in the center and two atoms of hydrogen around the central atom. There are also two pairs of electrons around the oxygen, which you can see at the Lewis structure.

1 Solid lines to represent bonds that are in the plane of the paper 2 Dashed lines to represent bonds that extend away from the viewer 3 Wedge-shaped lines to represent bonds oriented facing the viewer

Although there is no hard-and-fast rule for drawing a wedge and dash structure, most people find it easiest to visualize the three-dimensional shape of a molecule if the pair of bonds in the same plane as the paper is drawn next to each other, and the bonds in front of and behind the plane are also drawn next to each other…