Water is weird.
Yet without water's weirdness, Earth would be just another lifeless snowball in space. Theorists have offered numerous predictions about water's structure to explain its unusual properties, but nothing has been experimentally confirmed. The difficulty arises from the presence in all water of the hydronium ion, a water molecule with an extra hydrogen atom. Nonetheless, ionic clusters are largely responsible for water's uniqueness. Without them, water would be a gas at room temperature.