What is it about water that makes it so critical to life? What are those hydrogen and oxygen atoms doing?


I understand that all life needs it (mostly), but scientifically, what is it about such a simple molecule that makes it so important?

In: 4

Water has several properties that make it, perhaps not critical to life (we only have a few planets as a sample size after all, and the universe is… well… big). But it makes it very convenient for life to occur.

– Water is a great thermal battery. It can carry, store and move a lot of thermal energy. It provides cooling through evaporation (panting and sweating), which is critical for larger organisms that otherwise would not be able to regulate their core body heat
– Water is a great solvant. All kinds of chemicals will readily dissolve in water and be transported.
– Water is a great medium to be in. It will block a lot of harmful radiation, so fragile developing life can more easily grow in oceans.
– Water is abundant. It’s a combination of two common elements.

Water molecules are strongly polar, with partial positive charges on the two hydrogens and a partial negative charge on the one oxygen. The shared electrons of the O-H bonds spend more time with the O than with the Hs.

As a result, water can form charge-based attractions with other polar molecules and ions. When there are many water molecules it can form a shell around each polar molecule and ion. These shells allow many, many substances to dissolve in water, and that’s critical to life as we know it. Water enables chemical reactions in living plants and animals.