The highest known oxidation number for any element is +9, observed in the element Iridium.
Understanding Oxidation States
Oxidation state, also known as oxidation number, represents the hypothetical charge an atom would have if all bonds were ionic. It is a crucial concept in chemistry for understanding how electrons are transferred in chemical reactions.
- Oxidation occurs when an element's oxidation state increases, indicating a loss of electrons.
- Reduction occurs when an element's oxidation state decreases, indicating a gain of electrons.
The range of possible oxidation states for elements is vast, spanning from negative to positive values.
The Element with the Highest Oxidation State
Iridium (Ir), a rare, silvery-white transition metal, holds the record for the highest known oxidation state. This exceptional state of +9 is achieved in the compound tetroxoiridium(IX), where Iridium forms bonds with four oxygen atoms. This remarkable ability to attain such a high oxidation state is characteristic of some transition metals, which possess multiple d-orbitals that can participate in bonding.
Lowest Known Oxidation State
Conversely, elements can also exhibit very low oxidation states. The lowest known oxidation state is -4, which is observed for Carbon in compounds like methane (CH4). In methane, carbon is bonded to four hydrogen atoms, and due to hydrogen's lower electronegativity, carbon gains electrons, resulting in a negative oxidation state.
Examples of Oxidation States
To illustrate the extremes and common oxidation states, consider the following examples:
| Element | Compound / Ion | Oxidation State | Role |
|---|---|---|---|
| Iridium | Tetroxoiridium(IX) | +9 | Highest known |
| Carbon | Methane (CH4) | -4 | Lowest known |
| Oxygen | Water (H2O) | -2 | Common |
| Hydrogen | Water (H2O) | +1 | Common |
Understanding the concept of oxidation states is fundamental to comprehending chemical reactions, predicting reactivity, and balancing redox equations. Elements achieve various oxidation states depending on their electronic configuration and the elements they bond with, striving for stability.
