Nitrogen cycle

Nitrogen

An essential element for life, found in DNA, RNA, and proteins.

Nitrogen gas (\[\ce{N2}\])

Makes up about 78% of the Earth's atmosphere and is not directly usable by plants and animals.

Nitrogen cycle

The cyclic movement of nitrogen in different chemical forms between living organisms and the environment.

Nitrogen fixation

The process of converting atmospheric nitrogen gas into usable forms for plants and animals.

Lightning

A natural process that helps fix nitrogen by forming nitrate (\[\ce{NO3-}\]) from nitrogen gas and oxygen gas.

Nitrogen-fixing bacteria

Bacteria that convert nitrogen gas into ammonia (\[\ce{NH3}\]) using hydrogen gas (\[\ce{H2}\]).

Ammonification

The process of returning ammonia and ammonium ions to the environment through the decomposition of nitrogen-containing biological molecules.

Nitrification

The conversion of ammonia into nitrites (\[\ce{NO2-}\]) and then nitrates by nitrifying bacteria.

Denitrification

The process by which denitrifying bacteria convert nitrites and nitrates back into nitrogen gas, returning it to the atmosphere.

Bacteria

Living organisms that control many of the chemical transformations of nitrogen, making the nitrogen cycle occur faster than other nutrient cycles.