Chapter 2

Chemistry of Life

The Periodic Table and Organismal Elements
Although there are 92 naturally occurring elements, only 25 are necessary to human life. Furthermore, 96% of living matter is made up of only four of…
Atomic Structure
2.2: Atomic Structure
Elements are the simplest form of matter that exhibits unique physical and chemical properties and cannot be broken down further into any other…
Electron Behavior
2.3: Electron Behavior
Electrons are small subatomic particles that possess an electrical charge of negative one. As a result, they are attracted to—and revolve…
Electron Orbital Model
2.4: Electron Orbital Model
Electrons in an atom do not in fact simply circle the nucleus, and the exact location of an electron at any given moment cannot be accurately…
Molecules and Compounds
2.5: Molecules and Compounds
Not all elements have their outermost shells filled with electrons. To become more stable, they form molecules—two or more atoms chemically…
Molecular Shapes
2.6: Molecular Shapes
When understanding how different molecules interact with each other, it is helpful to know something about their molecular structure—the…
Carbon Skeletons
2.7: Carbon Skeletons
Organic compounds contain a structural backbone of carbon atoms referred to as the carbon skeleton. The element can form up to four bonds, which…
Chemical Reactions
2.8: Chemical Reactions
A chemical reaction is a process where a substance—an element or a compound—undergoes changes to produce a new substance. The starting…
Isotopes
2.9: Isotopes
All elements have one or more isotopes—nuclear variations in which the number of protons, also the atomic number, are the same but the number…
Covalent Bonds
2.10: Covalent Bonds
A covalent bond is formed when atoms share pairs of valence electrons, completing their outer, or valence, shells, creating a stable molecule. The…
Ionic Bonds
2.11: Ionic Bonds
An ionic bond is the attraction that holds two charged atoms, ions, together, creating a stable compound with atoms with complete valence shells.…
Hydrogen Bonds
2.12: Hydrogen Bonds
Hydrogen bonds are very weak attractions between one atom with a partial negative charge—an electronegative atom like oxygen—and a…
Van der Waals Interactions
2.13: Van der Waals Interactions
Van der Waal interactions are nonspecific attractions created when one atom comes close enough to another one to disturb its electrons—inducing…
States of Water
2.14: States of Water
For water, there are three main states in which it exists: solid or ice, liquid, and gas or steam. Which state water is in depends on the interaction…
pH
2.15: pH
The potential for a solution to donate or accept hydrogen ions determines whether it is an acid or a base. Acidic solutions donate protons, whereas…
Solvents
2.16: Solvents
A solvent is most often a liquid or gas that can dissolve other substances. The substance being dissolved is called a solute. When a solvent and a…
Redox Reactions
2.17: Redox Reactions
Oxidation-reduction, or redox, reactions transfer an electron from one atom, the reducing agent, to an atom that receives the electron, the oxidizing…
Adhesion
2.18: Adhesion
Adhesion occurs when two different molecules are attracted to each other. Water exhibits adhesive properties in the presence of polar…
Cohesion
2.19: Cohesion
Cohesion is the attraction between two identical molecules - such as water molecules. The partially charged negative oxygen on one molecule binds the…
Specific Heat
2.20: Specific Heat
Heat capacity refers to the amount of energy a substance can absorb. Water has a high heat capacity, so it takes a lot of heat to warm it up or even…
Vaporization
2.21: Vaporization
Vaporization changes a liquid substance into a gaseous or vaporous substance. To achieve this, kinetic energy must be greater than the intermolecular…
Measuring pH
2.22: Measuring pH
The pH meter is an electrical device that determines the acidity or basicity of aqueous solutions, one of the most commonly monitored parameters in…
Medicine: Differential Effects of Lipid-lowering Drugs
2.23: Medicine: Differential Effects of Lipid-lowering Drugs
Cholesterol lowering drugs are prescribed to favorably alter the levels of plasma LDL and HDL. This study uses a plaque array method with…
Medicine: Efflux Assays
2.24: Medicine: Efflux Assays
The cholesterol content of cells is maintained within the very tight limits. This article demonstrates an efflux assay designed to quantitate…
Biology: Biochemical and High Throughput Microscopic Assessment of Fat Mass
2.25: Biology: Biochemical and High Throughput Microscopic Assessment of Fat Mass
Methods to study fat stores in C. elegans have been time-consuming and have yielded inconsistent results. Here, Nile red stain is used to…