IB Biology A1.1 Notes

Water is the most essential molecule needed to sustain life on Earth. Also known as dihydrogen monoxide, it is composed of two hydrogen atoms covalently bonded to an oxygen atom. The sharing of electrons in these bonds is unequal, which means that water is a polar molecule!

Polar molecules with hydrogen and one of nitrogen, oxygen, or fluorine exhibit hydrogen bonding. Water fits this description, and thus exhibits hydrogen bonding between its molecules. Water’s polarity and its hydrogen bonding are the reason it is so versatile and the primary molecule we search for when attempting to detect alien life.