Use Lewis symbols and Lewis structures to diagram the formation of \(\mathrm{PF}_{3}\) from \(\mathrm{P}\) and \(\mathrm{F}\) atoms.

Valence electrons are the outermost electrons of an atom that are involved in forming chemical bonds. The number of valence electrons determines an atom's chemical properties and its ability to form bonds with other atoms. In the formation of phosphorus trifluoride ((PF_3), the valence electrons play a crucial role. Phosphorus has five valence electrons, while each fluorine atom has seven.

The Lewis symbols help us visualize these valence electrons as dots around the element's symbol. For example, the Lewis symbol for phosphorus (P) would be written with five dots around it representing its valence electrons. Similarly, for fluorine (F), we would draw seven dots around the symbol. The arrangement and pairing of these valence electrons through Lewis symbols become the foundation for predicting the bonding behavior of atoms in a molecule.

Covalent bonds form when atoms share pairs of valence electrons, creating a stable balance of attractive and repulsive forces between them. In our example of phosphorus trifluoride ((PF_3), each of the three fluorine atoms shares one of its valence electrons with phosphorus, resulting in the formation of single covalent bonds. These shared pairs of electrons, or bonding pairs, are represented as dashes in Lewis structures.

In (PF_3), there are three covalent bonds between the phosphorus and the fluorine atoms. Each bond consists of one electron from phosphorus and one from fluorine, contributing to a stable molecule. Covalent bonding is essential to molecular chemistry and dictates the structure and shape of a molecule, influencing both its physical and chemical properties.

The octet rule is a chemical rule of thumb which states that atoms tend to form molecules in a way that each atom has eight electrons in its valence shell, giving it the same electron configuration as a noble gas. The formation of phosphorus trifluoride ((PF_3) perfectly illustrates the octet rule. Each fluorine atom aims to complete its valence shell with eight electrons, and by sharing an electron with phosphorus through covalent bonding, every fluorine achieves this stable configuration.

Phosphorus, on the other hand, starts with five valence electrons and acquires three more from the fluorine atoms through bonding, reaching an octet. In the Lewis structure of (PF_3), this is evident as each atom is surrounded by eight electrons, satisfying the octet rule. This concept is fundamental in understanding the stability of most molecules, as following the octet rule generally leads to chemically stable configurations.