Bond angles are the angles formed between three atoms in a molecule, specifically between the bonds that connect them. These angles are crucial in determining the shape and structure of the molecule, which in turn influences its chemical properties and reactivity. For example, in a water molecule (H2O), the bond angle between the two hydrogen atoms is approximately 104.5 degrees. The ideal bond angles are often predicted by the VSEPR (Valence Shell Electron Pair Repulsion) theory, which states that electron pairs around a central atom will arrange themselves to minimize repulsion. Different molecular geometries, such as tetrahedral or trigonal planar, have characteristic bond angles that help define their shapes.