Chapter 2: The Chemical Foundation of Life Flashcards

Comprehensive vocabulary flashcards generated from OpenStax Biology 2e Chapter 2 covering key terms related to atomic structure, chemical bonds, water properties, pH, and organic carbon molecules.

Matter

Anything that occupies space and has mass.

Element

A unique form of matter with specific chemical and physical properties that cannot be broken down into smaller substances by ordinary chemical reactions.

Atom

The smallest unit of matter that retains all the chemical properties of an element.

Nucleus

The central region of an atom that contains protons and neutrons.

Proton

A sub-atomic particle located in the nucleus of an atom with a mass of $1\,amu$ and a charge of $+1$.

Neutron

An uncharged sub-atomic particle located in the nucleus of an atom with a mass of $1\,amu$ and a charge of $0$.

Electron

A negatively charged sub-atomic particle located in orbitals outside the nucleus with a mass of $0\,amu$ and a charge of $-1$.

Atomic Number

The distinct total number of protons present in the nucleus of an atom of a given element.

Atomic Mass

The mass of an atom expressed in atomic mass units ($amu$), roughly equal to the total number of its protons and neutrons.

Isotopes

Different forms of the same element that contain equal numbers of protons but different numbers of neutrons.

Radioisotopes

Unstable isotopes that decay over time by emitting neutrons, protons, and electrons.

Bohr Model

An early model of atomic structure depicting protons in the central nucleus and electrons revolving in circular orbits at specific distances from the nucleus.

Valence Shell

The outermost energy shell of an atom containing the electrons involved in chemical bonding.

Octet Rule

The principle that the most stable electron configuration occurs when an atom's outermost shell contains eight electrons.

Electron Orbital

A complexly shaped area around the atomic nucleus where an electron is mathematically most likely to be found.

Reactants

The initial chemical substances used at the beginning of a chemical reaction.

Products

The substances formed at the conclusion of a chemical reaction.

Irreversible Reaction

A chemical reaction that proceeds in one direction until all reactants are completely consumed.

Reversible Reaction

A chemical reaction in which reactants are converted into products, and products can simultaneously be converted back into reactants.

Chemical Bond

The attractive force that links atoms together to form molecules.

Covalent Bond

A strong chemical bond formed when two or more atoms share electrons.

Double Bond

A covalent bond formed when two pairs of electrons (four electrons total) are shared between two atoms.

Ionic Bond

A bond formed when metals lose electrons to become positively charged cations and nonmetals gain electrons to become negatively charged anions.

Polar Covalent Bond

A covalent bond in which electrons are shared unequally between atoms because one nucleus exerts a stronger electronegative pull on the shared electrons.

Non-Polar Covalent Bond

A covalent bond in which electrons are shared equally between atoms.

Hydrogen Bond

A weak interaction between the slightly positive charge ($\delta+$) of a hydrogen atom and the slightly negative charge ($\delta-$) of a more electronegative atom on another molecule.

Van der Waals Interactions

Weak attractions or interactions between two or more molecules in close proximity caused by transient changes in electron density.

Specific Heat Capacity

The amount of heat energy one gram of a substance must absorb in order to raise its temperature by one degree Celsius.

Heat of Vaporization

The amount of heat energy required to transform one gram of a liquid substance into a gas.

Solvent

A liquid substance capable of dissolving ions or other polar compounds.

Solute

A compound or substance dissolved in or mixed with a solvent.

Sphere of Hydration

A protective cluster of polar water molecules surrounding an individual charged ion in solution.

Cohesion

The intermolecular attraction between water molecules that holds them together, especially at a liquid-gas interface.

Surface Tension

The capacity of a liquid surface to withstand being ruptured when placed under tension or stress.

Adhesion

The attractive force between water molecules and other polar or charged molecules.

pH

A value indicating the acidity or alkalinity of a solution, defined mathematically as the negative base-10 logarithm of the hydrogen ion concentration ($-\log_{10}[\text{H}^+]$).

Buffer

A chemical system that plays a key role in maintaining the internal solutions of an organism at a near-neutral pH by accepting or donating hydrogen ions.

Hydrocarbon

An organic molecule consisting entirely of carbon and hydrogen atoms.

Aliphatic Hydrocarbon

A hydrocarbon consisting of linear or branched open chains of carbon atoms.

Aromatic Hydrocarbon

A hydrocarbon containing closed ring structures formed by carbon atoms, such as benzene.

Isomers

Molecules that share the same chemical formula but differ in the spatial arrangement of atoms or type of bonds.

Structural Isomers

Isomers that possess the same chemical formula but differ in the covalent arrangement of their constituent atoms.

Geometric Isomers

Isomers with different spatial arrangements of atoms around a rigid double covalent bond (e.g., cis vs. trans configurations).

Enantiomers

Molecules that share the same chemical formula and bonds but differ in their three-dimensional orientation, forming non-superimposable mirror images.

Functional Groups

Specific groups of atoms within a biological molecule that confer consistent and characteristic chemical properties to that molecule.