Science Glossary This glossary contains basic science terms. It will help you when you read or listen something about science and you will not understand the meaning of certain words and terms. atom noun The basic unit of a chemical element. Example: The water molecule, H 2 O, has two hydrogen atoms attached to the big oxygen atom at angles that discourage the formation of equilateral triangles. en: atome Your browser does not support the audio element. burette noun A graduated glass tube with a small aperture and stopcock for delivering measured quantities of liquid or for measuring the liquid or gas received or discharged. Example: Method 180.0 cm 3 of benzyl alcohol solution (2.33 x 10 -3 mol dm -3 benzyl alcohol, 0.68 mol dm -3 sulphuric acid, 20% acetic acid, with dilution factor 180 200), was dispensed from a burette into a 500 cm 3 conical flask. 20.0 cm 3 of pota...