Final answer:
The element being described is Nitrogen, which makes up 78% of Earth's atmosphere and is vital for proteins, fertilizers, and explosives.
Step-by-step explanation:
The element being described is Nitrogen. Nitrogen is a gaseous nonmetal that constitutes 78% of Earth's atmosphere by volume. It plays a crucial role in various biological and chemical processes. Nitrogen compounds are vital for the creation of proteins, which are essential for all living organisms, and are also used in fertilizers to promote plant growth. Moreover, nitrogen forms part of the structures of many explosives due to its ability to release a significant amount of energy when chemically combined with other elements. Nitrogen exists in the atmosphere predominantly as diatomic nitrogen (N₂).