Hard Base
| Formula / Notation | Hard base: high EN, low polarisability (e.g., F⁻, OH⁻, NH₃, H₂O) |
|---|---|
| Also Known As | Hard Lewis base, HSAB hard base, class (b) base (older), hard donor |
What is Hard Base?
In HSAB theory, a Lewis base that is small, has high electronegativity, is difficult to polarize, and is not easily oxidized. Hard bases form stronger bonds with hard acids. Examples include F⁻, OH⁻, NH₃, and water. They have low polarizability and strongly held electrons.
Formula & Notation
Other Names / Synonyms: Hard Lewis base, HSAB hard base, class (b) base (older), hard donor
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
In HSAB theory, a Lewis base that is small, has high electronegativity, is difficult to polarize, and is not easily oxidized. Hard bases form stronger bonds with hard acids. Examples include F⁻, OH⁻, NH₃, and water. They have low polarizability and strongly held electrons.
Hard base selectivity for hard metal ions explains: biological calcium transport (Ca²⁺ with O-donor carboxylate hard bases in proteins), bone mineralisation (Ca²⁺ and PO₄³⁻ — both hard), Al³⁺ toxicity mechanism (displaces Mg²⁺ from hard base enzyme sites), and chelation therapy design (EDTA uses har…
No specific safety concern. Understanding HSAB classification helps predict which chelating agents will effectively treat heavy metal poisoning: hard base donors (EDTA) for hard metal cations, soft base donors (dimercaprol, BAL) for soft metal cations like Hg²⁺ and As³⁺.
The formula or notation for Hard Base is: Hard base: high EN, low polarisability (e.g., F⁻, OH⁻, NH₃, H₂O)