* The specific reaction conditions: Temperature, pressure, presence of catalysts, and other reactants all influence reactivity.
* The other reactant: A gas that is highly reactive with one substance might be relatively unreactive with another.
However, some gases are generally considered highly reactive due to their inherent chemical properties:
Highly Reactive Gases:
* Fluorine (F2): The most electronegative element, fluorine is extremely reactive and readily forms strong bonds with many elements. It is a powerful oxidizing agent.
* Oxygen (O2): Essential for combustion, oxygen reacts readily with many substances, especially at elevated temperatures. It's a strong oxidizer.
* Ozone (O3): A highly reactive allotrope of oxygen, ozone is a powerful oxidizer and can damage living tissues.
* Chlorine (Cl2): A highly reactive halogen, chlorine is used as a disinfectant and in various industrial processes.
* Hydrogen (H2): While not as reactive as the halogens, hydrogen is flammable and can react explosively with oxygen.
Other Reactive Gases:
* Nitrogen oxides (NOx): Highly reactive compounds that contribute to air pollution.
* Sulfur dioxide (SO2): A major air pollutant and a precursor to acid rain.
* Carbon monoxide (CO): A colorless, odorless, and poisonous gas that can bind to hemoglobin, preventing oxygen transport in the blood.
Important Note: The reactivity of gases can be significantly influenced by their concentration, temperature, and the presence of catalysts.
It's important to remember that even "inert" gases like helium and neon can react under extreme conditions.
