How do atoms make compounds? Typically they join together in such a way that they lose their identities as elements and adopt a new identity as a compound. These connections are called chemical bonds . But how do atoms join together? Ultimately, it all comes down to electrons. Before we discuss how electrons interact, we need to introduce a tool to simply illustrate electrons in an atom. 11.1: Valence Electrons and the Periodic Table The chemical properties of elements is determined primarily by the number and distribution of valence electrons. 11.2: Representing Valence Electrons with Dots Lewis electron dot diagrams use dots to represent valence electrons around an atomic symbol. 11.3: Ionic Bonds The tendency to form species that have eight electrons in the valence shell is called the octet rule. One way of doing this is by gaining (for nonmetals) or losing (for metals) electrons to create ions which can be represented with Lewis electron dot diagrams. The attraction of oppositely charged ions caused by electron transfer is called an ionic bond. 11.4: Covalent Bonds Covalent bonds are formed when atoms share electrons. Lewis electron dot diagrams can be drawn to illustrate covalent bond formation. In Lewis structures, we encounter bonding pairs, which are shared by two atoms, and lone pairs, which are not shared between atoms. 11.5: Multiple Covalent Bonds Covalent bonds are formed when atoms share electrons. Double bonds or triple bonds between atoms may be necessary to properly illustrate the bonding in some molecules. 11.6: Writing Lewis Structures for Molecular Compounds The Lewis structure of a molecule shows how the valence electrons are arranged among the atoms of the molecule. For more complex molecules, structures can be created by following four basic steps. 11.7: Predicting the Shapes of Molecules The approximate shape of a molecule can be predicted from the number of electron groups and the number of surrounding atoms. 11.8: Templates Page for Lewis Diagrams 11.9: For Future Use 11.10: Exercises Template:HideTOC Thumbnail Chapter 11: A covalent bond in a hydrogen molecule. (Jacek FH via Wikimedia Commons)