In general terms how did the atoms that make up chitin go fromatomospheric gases to being part of an arthropods?

The atoms that make up chitin, primarily carbon, hydrogen, oxygen, and nitrogen, originate from atmospheric gases and organic matter through various biological and geological processes. Carbon dioxide is absorbed by plants during photosynthesis and converted into organic compounds. These compounds are then consumed by animals, including arthropods, which incorporate the elements into their bodies. Over time, as arthropods grow and develop, they synthesize chitin, forming a key structural component of their exoskeletons.