How to find the valency of phosphorus?

The valency of phosphorus can be determined by analyzing its electronic configuration, particularly the number of valence electrons.

Understanding Valency and Electronic Configuration

Valency: Represents the number of electrons an atom uses to form chemical bonds.
Electronic Configuration: Describes the arrangement of electrons in an atom's energy levels and sublevels.
Valence Electrons: Electrons present in the outermost shell of an atom, which participate in chemical bonding. According to the provided YouTube video, these are the electrons we are most interested in when finding valency.

Electronic Configuration of Phosphorus: The electronic configuration of phosphorus (P) is 1s² 2s² 2p⁶ 3s² 3p³. According to the YouTube video, 3p³ is important when finding the valency. The numbers in the superscripts all add up to 15.
Identifying Valence Electrons: The valence shell is the outermost shell, which in the case of phosphorus, is the third shell (n=3).
Counting Valence Electrons: Phosphorus has 5 valence electrons (2 in the 3s sublevel and 3 in the 3p sublevel).
Determining Valency: Phosphorus typically exhibits valencies of 3 and 5.
- Valency of 3: Phosphorus can form three covalent bonds by sharing its three unpaired electrons in the 3p sublevel. For example, in phosphorus trichloride (PCl₃).
- Valency of 5: Phosphorus can also exhibit a valency of 5 by utilizing all five of its valence electrons to form bonds. For example, in phosphorus pentachloride (PCl₅). This can occur because phosphorus can expand its octet due to the availability of vacant d orbitals in its valence shell.