Describe possible early atmospheric gases including methane and ammonia.

In the subtopic The Earth's early atmosphere, this learning objective focuses on describe possible early atmospheric gases including methane and ammonia. Within The composition and evolution of the Earth's atmosphere, students should explain this idea in the exact curriculum context rather than as an isolated fact. Approved keywords for this objective include ammonia and methane. methane means a colorless, odorless gas that is a major component of natural gas and a possible early atmospheric gas. Avoid students often confuse methane and ammonia as being the same gas when describing possible early atmospheric gases; instead remember that methane (CH₄) is a hydrocarbon, while ammonia (NH₃) is a nitrogen compound. Make sure to distinguish between their chemical formulas and properties. For exam answers, when answering, list methane (CH₄) and ammonia (NH₃) as likely early atmospheric gases, noting they are reduced gases that could have been released by volcanic activity.