HYPERVALENT COMPOUND Meaning and
Definition
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A hypervalent compound refers to a molecule or ion that contains a central atom that exceeds its conventional valence electron limit. Valence electrons are the outer shell electrons of an atom involved in chemical bonding. Typically, atoms tend to form bonds by sharing, gaining, or losing electrons to attain a more stable electron configuration, such as the octet rule in which atoms prefer to have eight valence electrons.
However, in hypervalent compounds, the central atom is capable of accepting additional electrons beyond its conventional valence limit, leading to an expanded electron shell. This phenomenon is particularly observed in elements from the third row of the periodic table onward, such as phosphorus, sulfur, and chlorine.
Hypervalency is facilitated through the utilization of empty d-orbitals in the central atom or through the extension of its valence shell beyond the octet limit. This allows the central atom to accommodate more than the usual number of electrons and form additional bonds. Consequently, hypervalent compounds often exhibit a coordination number greater than the expected valence limit for a given atom, resulting in an expanded molecular structure.
Hypervalent compounds have diverse applications in various branches of chemistry, including catalysis, organic synthesis, and medicinal chemistry. They possess unique properties due to their expanded coordination, allowing for new bonding arrangements and potential reactivity. However, it is important to note that the concept of hypervalency remains a topic of ongoing research and debate, as there are still some inconsistencies and exceptions to the traditional valence electron rules that continue to be explored.
Etymology of HYPERVALENT COMPOUND
The word "hypervalent" comes from the combination of two components: "hyper" and "valent".
1. "Hyper": This prefix comes from the Greek word "huper" (ὑπέρ), meaning "above" or "beyond". It is commonly used to emphasize excess or exaggeration.
2. "Valent": This term is derived from the Latin word "valens", which means "strong" or "powerful". In chemistry, it refers to the combining capacity of an atom or group of atoms, also known as the valence.
Thus, when combined, the term "hypervalent" denotes a compound where the valence of the central atom exceeds its usual or expected limit. It suggests that the atom possesses more bonding capability than its conventional valence suggests.
