Why do some elements exist as biatomic gases?

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Discussion Overview

The discussion revolves around the nature of certain gases, specifically why elements like oxygen and hydrogen exist primarily as diatomic molecules rather than in monoatomic form. It explores theoretical aspects of molecular bonding and the conditions under which these gases exist.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants propose that diatomic gases exist due to their bonding characteristics, with hydrogen, fluorine, and chlorine forming one bond, while nitrogen and oxygen can form multiple bonds.
  • One participant notes that diatomic gases can be dissociated into monoatomic forms under high energy conditions, but will recombine upon cooling.
  • Another participant questions whether the focus should be on why gases are diatomic or why diatomic elements tend to be gases, suggesting both angles are interesting.
  • It is mentioned that among the first 103 elements, six are monoatomic gases that do not form molecules, while five are diatomic gases.
  • Some participants clarify that not all diatomic elements are gases, citing bromine and iodine as exceptions.
  • Concerns are raised about the short half-lives of certain elements like astatine, which complicate their study in solid forms.

Areas of Agreement / Disagreement

Participants express differing views on the reasons behind the diatomic nature of certain gases and the implications of their bonding properties. The discussion remains unresolved with multiple competing perspectives presented.

Contextual Notes

Limitations include the dependence on specific conditions for dissociation and recombination of gases, as well as the unclear status of certain elements due to their short half-lives affecting their classification.

scientifico
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Hello, why gases like Oxygen, Hydrogen, etc are biatomic ? do they exist in monoatomic form ?
thanks
 
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scientifico said:
Hello, why gases like Oxygen, Hydrogen, etc are biatomic ? do they exist in monoatomic form ?
thanks

sure they do. when you re-enter the atmosphere the immense heat generated by drag and the catalytic properties of the metal surface break atmospheric oxygen and nitrogen within the hypersonic flow into atomic gases.
 
I wonder if the question should be not reversed - is it about why gases are diatomics, or why diatomics tend to be gases...
 
Borek said:
I wonder if the question should be not reversed - is it about why gases are diatomics, or why diatomics tend to be gases...
Maybe the first, but both questions are interestings
 
Out of the 11 elements among the first 103 which are gases at atmospheric pressure and room temperature, the majority (6) are monoatomic. These 6 never form molecules (with themselves).

The remaining 5 biatomic gases can all be dissociated into atoms - by application of large amounts of energy. On cooling, they recombine.

The reason hydrogen, fluorine and chlorine are biatomic is that they readily form one and only one bond. Once that is saturated, they do not readily form additional bonds to network into solids.

The reason nitrogen and oxygen are biatomic is that they being second period elements readily form multiple bonds, again saturating their bonds so as not to form networks.

Not all diatomic elements are gases. Bromine and iodine are not. Talking of first 103, not sure about astatine - the inconveniently short halflives (not over 8 hours) hamper crystal structure investigations...
 

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