\(\mathrm{CF}_{4}, \mathrm{SF}_{4}\) and \(\mathrm{XeF}_{4}\) contain the following electronic structure on their central atoms. Which one is correct option? (a) 1,2 and 3 lone pairs of electrons respectively (b) 0,1 and 2 lone pairs of electrons respectively (c) 1,1 and 1 lone pairs of electrons respectively (d) No lone pairs of electrons on any molecule

Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used to predict the shape of individual molecules based on the extent of electron-pair electrostatic repulsion. In simple terms, it explains how the pairs of electrons in the outermost shell, or valence shell, of an atom repel each other and move as far apart as possible. This model is particularly useful because the geometric arrangement of atoms in a molecule largely affects the molecule's properties and reactivity.

The main idea behind VSEPR theory is that the molecule's shape adjusts so that valence electron pairs stay as distant from each other as possible to minimize repulsion. This results in predictable molecular shapes and bond angles. Electrons will first fill up space in the molecular structure as bonding pairs between atoms, after which any remaining electrons become non-bonding pairs, also called lone pairs, which still influence the molecule's shape.

For instance, in the step-by-step solution, the VSEPR theory helps determine that the molecule SF4 has a 'see-saw' geometry due to the presence of one lone pair that distorts the tetrahedral arrangement of the surrounding atoms.

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. The geometry of a molecule can be linear, bent, tetrahedral, trigonal-planar, see-saw, and various other shapes, depending on how many bonds and lone pairs of electrons are present in the compound.

The geometry is critical to understanding the molecule’s function and reactivity. For example, the step-by-step solution identifies CF4 as having a tetrahedral geometry, meaning it has four bond pairs and no lone pairs, resulting in a symmetric shape. In contrast, SF4's 'see-saw' shape is a result of five regions of electron density (four bonding pairs and one lone pair) around the central sulfur atom. A square planar shape like in XeF4 is a result of six regions of electron density: four bonding pairs and two lone pairs.

Understanding molecular geometry is not just useful for predicting physical and chemical properties, but it is also a key concept when it comes to understanding how molecules interact and react with each other.

Valence electrons are the outermost electrons of an atom that are involved in chemical bonding. These electrons have the highest energy level and are held less tightly to the nucleus, making them more available for interactions with other atoms. They are the electrons you see when drawing Lewis structures and are used to form bonds with other atoms. The valence electrons are also the ones which will pair up in the molecule's structure, whether as bonding pairs or as lone pairs.

In the context of the exercise, carbon has four valence electrons which it shares with fluorine atoms in CF4, explaining why there are zero lone pairs. Sulfur has six valence electrons, but in SF4, after the formation of four bonds with fluorine atoms, there are still two electrons left, which form one lone pair. Xenon has eight valence electrons, and in XeF4, after forming four bonds with fluorine atoms, four electrons remain, thus creating two lone pairs.

Clearly, the valence electrons play a vital role in determining a molecule's structure, and hence, its properties and the way it will interact with other substances in chemical reactions.