Question

What are the electron geometry and the molecular geometry of water?

Answer 1

Hint: To know the electron geometry and the molecular geometry of water, we need to study the shape of water molecules. We also need to understand the difference between electron geometry and molecular geometry. To determine the geometry of a water molecule, we can use VSEPR theory to determine the hybridization. It is not structured linearly.

Complete answer:
To be able to predict the shape of molecules, it is important to learn about the Valence Shell Electron Pair Repulsion Theory, known as the VSEPR Theory. This theory provides a simple procedure to predict the shape of the molecule. VSEPR theory is used to forecast how electron pairs would be arranged around core atoms in molecules, particularly simple and symmetric molecules. The main postulates of VSEPR theory are as follows:
(i) The shape of a molecule depends upon the number of valence shell electron pairs (bonded or non bonded) around the central atom.
(ii) Pairs of electrons in the valence shell repel one another since their electron clouds are negatively charged.
(iii) These pairs of electrons tend to occupy such positions that minimize repulsion and thus maximize the distance between them.
(iv) The valence shell is taken as a sphere with the electron pairs localizing on the spherical surface at a maximum distance from one another.
(v) A multiple bond is treated as if it is a single electron pair and the two or three electron pairs of multiple bonds are treated as a single super pair.
(vi) Where two or more resonance structures can represent a molecule, the VSEPR model applies to any such structure.
The repulsive interactions of electron pairs decrease in the order: Lone pair-Lone pair>Lone pair-Bond pair>Bond pair-Bond pair.
For the prediction of geometrical shapes of molecules with the help of VSEPR theory, it is convenient to divide molecules into two categories as (i)molecules in which the central atom has no lone pair and (ii) molecules in which the central atom has one or more lone pairs.
The electron pairs that aren't involved in bonding, as well as the electron cloud density, are taken into consideration in electronic geometry. The two hydrogen bonds count as two-electron clouds, and the two-electron pairs count as another two, for a total of four. The electronic geometry of the VSEPR is tetrahedral, with four electron areas. Only the electrons involved in bonding are examined in molecular geometry. As a result, just the two bonds to H are considered. The form would not be linear since the unpaired electrons would prevent such a shape. Because electrons repel one another, they adopt forms that help to decrease electron repulsion.
Hence, the electron geometry of water is the tetrahedral shape and the molecular geometry of water is a bent shape.

Fig. Structure of water.

Note:
It must be noted that water is a simple molecule that is made up of one oxygen atom linked to two hydrogen atoms. Because of the two lone pairs of electrons on the oxygen atom, the molecule takes on a bent shape. The \[H - O - H\]bond angle is around \[105\] degrees, which is slightly less than the optimum \[109.5\] degrees of a \[s{p^3}\]hybridized atomic orbital.