Why is the nitrogen cycle important?

Nitrogen is important to life because it is a key part of amino and nucleic acids. Also, it is an important part of ATP, which is the basic energy molecule for living things. Neither plants or animals can obtain nitrogen directly from the atmosphere. Instead, they depend on a process known as nitrogen fixation.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.