how big is a molecule of water
In addition to mass, we can also measure how big a molecule is. A water molecule is about 0.27 of a nanometer across. DNA is about 2 nanometers across and can stretch out to meters in length. Amazing, when you think about that length of DNA being stuffed inside a cell. But that is because it is so thin, about 1/1,000,000,000 as thick as it is long.