Home > Encyclopedia of Science > Molecule

• Words to Know
• Formation of compounds
• Polar and nonpolar molecules
• Formulas

A molecule is a particle consisting of two or more atoms joined to each other by means of a covalent bond. (Electrons are shared in covalent bonds.) There are a number of different ways of representing molecules. One method is called an electron-dot diagram, which shows the atoms included in the molecule and the electron pairs that hold the atoms together. Another method is the ball-and-stick model, in which the atoms present in the molecule are represented by billiard-ball-like spheres; the bonds that join them are represented by wooden sticks. A third method is called a space-filling model, which shows the relative size of the atoms in the molecule and the way the atoms are actually arranged in...