Atoms, which consist of protons, neutrons, and electrons, are the smallest units of an element that retain all of the properties of that element. Electrons can transfer, share, or cause charge disparities between atoms to create bonds, including ionic, covalent, and hydrogen bonds, as well as van der Waals interactions

Hydrogen bonds allow ions and other polar molecules to dissolve in water. All of the 98 elements that occur naturally have unique qualities that allow them to combine in various ways to create molecules, which in turn combine to form cells, tissues, organ systems, and organisms.

ion — atom or chemical group that does not contain equal numbers of protons and electrons. van der Waals interaction — very weak interaction between molecules due to temporary charges attracting atoms that are very close together. electron — negatively charged subatomic particle that resides outside of the nucleus in the electron orbital; lacks functional mass and has a negative charge of -1 unit. element — one of 118 unique substances that cannot break down into smaller substances; each element has unique properties and a specified number of protons.