Chapter 2

Chemistry of Life

The Periodic Table and Organismal Elements
Overview Elements are the smallest units of matter that cannot be broken down further by chemical processes. There are 118 known elements, but not…
Atomic Structure
2.2: Atomic Structure
Overview All matter is composed of atoms, the smallest individual units of elements. Each atom is made up of three subatomic particles: protons,…
Electron Behavior
2.3: Electron Behavior
Overview Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They…
Electron Orbital Model
2.4: Electron Orbital Model
Overview Orbitals are the areas outside of the atomic nucleus where electrons are most likely to reside. They are characterized by different energy…
Molecules and Compounds
2.5: Molecules and Compounds
Overview An atom is most stable when its valence shell—the outermost energy shell that contains electrons—is full. Most elements do not…
Molecular Shapes
2.6: Molecular Shapes
Overview The shape of a molecule contributes to its function and its interactions with other molecules. Over the years, many different models have…
Carbon Skeletons
2.7: Carbon Skeletons
Overview The backbone of all organic compounds is a carbon skeleton. Each carbon atom can make four bonds, and as the carbon skeleton increases in…
Chemical Reactions
2.8: Chemical Reactions
Overview A chemical reaction is a process by which the bonds in the atoms of substances are rearranged to generate new substances. Matter cannot be…
Isotopes
2.9: Isotopes
Elements have a set number of protons that determines their atomic number. For example, all atoms with eight protons are oxygen. However, the number…
Covalent Bonds
2.10: Covalent Bonds
Overview When two atoms share electrons to complete their valence shells they create a covalent bond. An atom’s electronegativity—the…
Ionic Bonds
2.11: Ionic Bonds
Overview When atoms gain or lose electrons to achieve a more stable electron configuration they form ions. Ionic bonds are electrostatic attractions…
Hydrogen Bonds
2.12: Hydrogen Bonds
Hydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has…
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
Water exists in three main states: solid (ice), liquid, and gas (steam). The state water is in depends on the intermolecular forces that draw water…
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 a substance, most often a liquid, that can dissolve other substances. Here, the substance being dissolved is called a solute. When a…
Redox Reactions
2.17: Redox Reactions
Oxidation-reduction, or redox, reactions change the oxidation states of atoms via the transfer of electrons from one atom, the reducing agent, to…
Adhesion
2.18: Adhesion
Adhesion occurs when one type of molecule is attracted to a different kind of molecule. Water exhibits adhesive properties in the presence of polar…
Cohesion
2.19: Cohesion
Cohesion is the attraction between molecules of the same type - such as water molecules. The partially charged negative oxygen of one water molecule…
Specific Heat
2.20: Specific Heat
A substance’s specific heat capacity refers to the amount of energy required to heat one gram of the substance by one degree. Water has a high…
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…
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…