How many degrees is a bent molecule?

As a domain expert in the field of molecular geometry, I can provide a detailed explanation of how to determine the degree of bending in a molecule. The degree of bending in a molecule is determined by its molecular geometry, which is the three-dimensional arrangement of atoms within a molecule. This arrangement is influenced by the valence shell electron pair repulsion (VSEPR) theory, which states that electron pairs around a central atom will arrange themselves to minimize repulsion. When we talk about a "bent" molecule, we are typically referring to a molecule that has a trigonal planar electron-pair geometry but a tetrahedral molecular geometry. This is because the central atom has four electron pairs in its valence shell, but three of these are bonding pairs involved in forming covalent bonds with other atoms, and one is a lone pair that does not participate in bonding. The VSEPR theory predicts that the three bonding pairs will arrange themselves as far apart as possible, which in a tetrahedral geometry would be at 109.5 degrees from each other. However, the presence of the lone pair distorts this arrangement, causing the molecule to be "bent" or "V-shaped." The bond angle in a bent molecule is typically less than the 109.5 degrees of a perfect tetrahedron due to the greater repulsion exerted by the lone pair compared to the bonding pairs. Note: For bent molecular geometry when the electron-pair geometry is trigonal planar, the bond angle is slightly less than 120 degrees, around 118 degrees. For trigonal pyramidal geometry, the bond angle is slightly less than 109.5 degrees, around 107 degrees. It's important to distinguish between the electron-pair geometry and the molecular geometry. While the electron-pair geometry refers to the arrangement of all electron pairs (both bonding and non-bonding), the molecular geometry specifically refers to the arrangement of the atoms within the molecule. Let's consider some examples to illustrate this concept: 1. Water (H2O): Water is a bent molecule. It has a central oxygen atom with two hydrogen atoms bonded to it and two lone pairs of electrons. The electron-pair geometry around the oxygen atom is tetrahedral, but the molecular geometry, considering only the positions of the hydrogen atoms, is bent with a bond angle of about 104.5 degrees. 2. Sulfur Dioxide (SO2): Sulfur dioxide is another example of a bent molecule. The central sulfur atom is bonded to two oxygen atoms and has one lone pair of electrons. The electron-pair geometry is trigonal planar, but the molecular geometry is bent with a bond angle of approximately 119 degrees. 3. Ammonia (NH3): Ammonia is a trigonal pyramidal molecule, which is a type of bent molecule. The nitrogen atom is bonded to three hydrogen atoms and has one lone pair of electrons. The bond angle in ammonia is slightly less than the tetrahedral angle of 109.5 degrees, typically around 107 degrees. In summary, the degree of bending in a molecule is a result of the interplay between the number of bonding and non-bonding electron pairs and their repulsive interactions. The bond angles in bent molecules are typically less than the ideal angles predicted by the electron-pair geometry due to the influence of lone pairs. Understanding these concepts is crucial for predicting and interpreting the shapes and reactivity of molecules in chemistry.

Note: for bent molecular geometry when the electron-pair geometry is trigonal planar the bond angle is slightly less than 120 degrees, around 118 degrees. For trigonal pyramidal geometry the bond angle is slightly less than 109.5 degrees, around 107 degrees.