The chemical element represented by the letter N is nitrogen. Nitrogen is a non-metal gas at room temperature and constitutes approximately 78% of the Earth's atmosphere, playing a crucial role in various biological processes. It is essential for the synthesis of amino acids, proteins, and nucleic acids, making it vital for life. Nitrogen is part of the nitrogen cycle, where it is converted into other forms, such as ammonia and nitrates, through processes like nitrogen fixation and decomposition. As a key component in fertilizers, nitrogen supports agriculture and food production, emphasizing its importance to both the environment and human societies.