H2O (water)

Water (H₂O) is a molecule composed of two hydrogen atoms bonded to one oxygen atom. It exists naturally as a liquid at Earth's surface and is essential for all known forms of life. Water's unique properties include its ability to dissolve many substances, its high specific heat (which helps regulate temperature), and its surface tension. These characteristics make water vital for processes like transporting nutrients, supporting chemical reactions, and maintaining environmental stability. Its versatility and abundance make water fundamental to the planet's ecosystems, climate, and biological functions.