BharatNotes Valence
nounUsage in a UPSC answer
A welfare scheme succeeds not merely on its fiscal design but on its emotional valence, for a policy that citizens perceive as dignifying rather than demeaning commands far greater participation and legitimacy.
Synonyms
Antonyms
Word Family
valency (n), valent (adj, in compounds), bivalent (adj), monovalent (adj), multivalent (adj)
Root
Latin valentia = strength, capacity; from valēre = to be strong; adopted into chemistry mid-19th c.
Etymology
From Latin valentia ("strength, capacity"), from valēre ("to be strong"); adopted into chemistry in the mid-19th century.
Memory Hook
Valence shares its root with "value" and "valiant" (Latin valere, to be strong) - think of the "strength" of an atom's bonds or the emotional "pull" something has on you.
How This Word Works in UPSC Writing
The combining capacity of an atom, fixed by how many electrons it must lose, gain or share to reach a stable outermost shell. The organising idea is the octet rule, that atoms tend towards eight electrons in the valence shell, with the light elements completing a duplet of two instead, which is why the noble gases with already-complete shells are so unreactive that their discovery required a new group in the periodic table. Valence explains periodicity directly: elements in the same group share the number of valence electrons and therefore show similar chemical behaviour, which is the property the table was built to display. Note that many elements show variable valency, iron being the standard case with two and three, because electrons can be removed from more than one sub-shell at comparable energy cost.
Don’t Confuse It With
Valence or valency is the combining capacity of an atom and is written without a sign. Oxidation state is signed, positive or negative, and tracks notional electron transfer, so sulphur has valency two in one compound and an oxidation state that ranges from minus two to plus six across others. Valence electrons are those in the outermost shell that determine the capacity. Electronegativity concerns how strongly an atom pulls shared electrons, which is a different question from how many it shares. Note the wholly separate psychological sense of valence, meaning the positive or negative pull of an experience, which is the sense used in the sentence above.
Hindi Meaning
संयोजकता (sanyojaktā); संयोजकता इलेक्ट्रॉन for valence electrons.
Common Questions
- What is valency?
- The combining capacity of an atom, determined by the number of electrons it loses, gains or shares to attain a stable outermost shell.
- How is valency different from oxidation state?
- Valency is an unsigned count of combining capacity, while oxidation state carries a positive or negative sign and tracks the notional transfer of electrons in a compound.
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