Biochemical Origin of Life - Second step: Origin of Molecules and Simple Inorganic Compounds

• Temperature of primitive Earth was extremely high (about 5000–6000°C).
• Under such high temperature, elements like hydrogen, oxygen, carbon, and nitrogen could not remain in a free state.
• These elements combined to form simple inorganic compounds such as oxides, carbides, and nitrides.
• Water was present as superheated steam, not as liquid.

Reactive elements (H, C, O, and N) combined due to high-energy conditions.

Formed basic inorganic compounds:

• Oxides (from oxygen)
• Carbides (from carbon)
• Nitrides (from nitrogen)

These were among the earliest chemical substances on Earth and formed the base for later chemical evolution.

• Gradual cooling of Earth allowed superheated steam to condense into rain.
• Continuous rainfall over a long period led to the accumulation of water on the surface.
• Hot boiling seas/oceans were formed.

These early oceans contained:

• Dissolved gases (methane, ammonia)
• Minerals and salts.

Around 3600 million years ago, Earth had:

• Solid crust
• Active volcanic eruptions
• Hot oceans.

Atmosphere was reducing in nature (no free oxygen).

Major gases present:

• Hydrogen (H₂)
• Methane (CH₄)
• Ammonia (NH₃)
• Carbon dioxide (CO₂)
• Nitrogen (N₂)
• Water vapour (H₂O).

• Due to extremely high temperatures on early Earth, elements like hydrogen, carbon, oxygen, and nitrogen combined to form simple inorganic compounds such as oxides, carbides, and nitrides.
• As the Earth cooled, water vapour condensed into rain, leading to the formation of oceans containing dissolved gases like methane, ammonia, minerals, and salts.
• The primitive Earth had a reducing atmosphere rich in hydrogen, methane, ammonia, carbon dioxide, and water vapour, with no free oxygen present.