# 4: Structure and Function

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The three dimensional shape or configuration of a molecule is an important characteristic. This shape is dependent on the preferred spatial orientation of covalent bonds to atoms having two or more bonding partners.

• 4.1: Lewis Electron Dot Structures
Ionic substances are completely held together by ionic bonds. The full charges of the ions (for example, Na+ and Cl− in sodium chloride) cause electrostatic interactions that result in a stable crystal lattice. Ionic compounds exist as extended, orderly arrangements of ions. This is quite different from the structure of molecular substances, which take the form of collections of individual molecules.
• 4.2: Representing Structures
Lewis structures are great for small molecules but can be complicated when dealing with large molecules. There are a variety of ways that we can represent molecules that provide use with enough information without creating a complicated figure. T
• 4.3: Electron Group Geometry
Electron group geometry is the three-dimensional arrangement of atoms in a molecule. The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound. Those properties include melting and boiling points, solubility, density, and the types of chemical reactions that a compound undergoes. In this section, you will learn a technique to predict molecular shape based on a molecule's Lewis electron dot structure.
• 4.4: Functional Groups
With over twenty million known organic compounds in existence, it would be very challenging to memorize chemical reactions for each one. Fortunately, molecules with similar functional groups tend to undergo similar reactions. A functional group is defined as an atom or group of atoms within a molecule that has similar chemical properties whenever it appears in various compounds. Even if other parts of the molecule are quite different, certain functional groups tend to react in certain ways.
• 4.5: Structure and Function (Exercises)
These are homework exercises to accompany Chapter 4 of the University of Kentucky's LibreText for CHE 103 - Chemistry for Allied Health. Solutions are available below the questions.

This page titled 4: Structure and Function is shared under a CK-12 license and was authored, remixed, and/or curated by CK-12 Foundation via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.