Chapter 2: The Chemical Foundation of Life

Vocabulary practice flashcards covering atomic structure, chemical bonding, water properties, reactions, pH, buffers, and organic functional groups from Chapter 2 lecture notes.

Matter

Anything that has mass and occupies space, existing as a solid, liquid, or gas.

Element

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

Atom

The smallest unit of matter that retains all chemical properties of an element and serves as the fundamental building block of all matter.

Nucleus

The central structure of an atom containing protons and neutrons.

Proton

A positively charged subatomic particle located in the nucleus of an atom whose quantity determines the atomic number.

Neutron

A neutral subatomic particle with no electrical charge located in the nucleus of an atom.

Electron

A negatively charged subatomic particle found in orbitals or shells surrounding the nucleus.

Atomic Number (Z)

The unique number of protons in an atom that distinguishes an element and determines its chemical properties.

Atomic Mass (A)

The total number of protons and neutrons in an atom, calculated as $\text{Atomic Mass} = \text{Protons} + \text{Neutrons}$.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Radiocarbon Dating

A type of radioactive dating using the decay of $C^{14}$ to estimate the age of organic materials such as fossils, wood, and bones up to approximately $50{,}000$ years.

Ötzi the Iceman

A naturally mummified man from the Copper Age discovered in the Alps in 1991, determined by radiocarbon dating to have lived around 5,300 years ago.

Bohr's Model

An atomic model proposing that electrons move in fixed circular orbits (K, L, M, N) around the nucleus at specific energy levels.

Valence Shell

The outermost electron shell of an atom.

Valence Electrons

The electrons contained in the outermost shell of an atom that control its chemical reactivity.

Octet Rule

The principle that main-group elements are most stable when their valence shell contains 8 electrons.

Ion

A charged atom formed when an atom gains or loses electrons.

Cation

An overall positively charged ion formed when an atom loses electrons.

Anion

An overall negatively charged ion formed when an atom gains electrons.

Primary Bonds

Strong intramolecular forces that occur by sharing or transferring electrons between atoms, including ionic and covalent bonds.

Secondary Interactions

Weak intermolecular forces that do not involve sharing or transfer of electrons, such as hydrogen bonds, Van der Waals forces, and hydrophobic interactions.

Ionic Bond

A bond formed when one atom completely transfers electrons to another, creating positively and negatively charged ions, occurring when the electronegativity difference is greater than 1.8.

Electronegativity

The tendency of an atom to attract electrons toward itself.

Covalent Bond

A chemical bond formed when electrons are shared between atoms to achieve a stable outer shell.

Polar Covalent Bond

A covalent bond in which bonding electrons are shared unequally between two atoms, creating partial charges.

Nonpolar Covalent Bond

A covalent bond in which bonding electrons are shared equally between two atoms with no partial charges.

Electronegativity Difference Scale

A classification scale for chemical bonds where 0.0 to 0.4 represents nonpolar covalent, 0.4 to 1.8 represents polar covalent, and greater than 1.8 represents ionic bonds.

Hydrogen Bond

A weak attraction between a hydrogen atom bonded to a highly electronegative atom (such as nitrogen, oxygen, or fluorine) and another nearby electronegative atom.

Hydrophobic Interaction

The tendency of nonpolar substances to cluster together in water to be excluded from an aqueous environment.

Hydrophobic Molecules

Nonpolar molecules that fear water and tend to cluster away from aqueous environments.

Hydrophilic Molecules

Polar or ionic molecules that love water and readily interact with or dissolve in water.

Anabolism

Metabolic synthesis reactions in which small molecules are assembled into larger ones, requiring energy.

Catabolism

Metabolic pathways where large molecules are broken down into small ones, releasing energy.

Solute

The substance that gets dissolved in a solution.

Solvent

The substance in a solution that does the dissolving.

Solution

A homogeneous mixture composed of a solute dissolved in a solvent.

Cohesion

The property of like molecules sticking together, such as water molecules attracting other water molecules.

Surface Tension

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

Adhesion

The tendency of molecules to stick to other, different types of molecules.

Specific Heat

The quantity of heat required to raise the temperature of $1\,g$ of a substance by $1\,^\circ\text{C}$.

Heat of Vaporization

The quantity of heat required to induce a phase change from liquid to vapor (also known as enthalpy of vaporization).

Acid

Any substance that releases hydrogen ions ($H^+$) in aqueous solutions, forming hydronium ions ($H_3O^+$).

Base

A substance that forms hydroxide ions ($OH^-$) in solution, combining with $H^+$ to lower $[H^+]$ concentration and increase the pH.

Buffer

A solution that resists changes in pH when small amounts of acid or base are added, essential for maintaining homeostasis.

Redox Reaction

A chemical reaction involving the transfer of electrons between two chemical species.

Oxidation

The loss of electrons during a chemical reaction.

Reduction

The gain of electrons during a chemical reaction.

Organic Molecule

A molecule containing carbon-to-hydrogen bonds and often carbon-to-carbon bonds.

Saturated Hydrocarbons

Hydrocarbons containing a skeleton of carbon atoms with all other open bonds taken up by hydrogen atoms, ending with the suffix -ane.

Alcohols

Organic molecules containing an attached hydroxyl group ($-OH$), designated by the suffix -ol.

Aldehydes

Organic molecules containing an aldehyde group attached to the end of the molecule, designated by the suffix -aldehyde.

Organic Acids

Organic molecules containing an attached carboxyl group ($-COOH$).

Organic Phosphates

Organic molecules containing an attached phosphate group, designated by the prefix phospho- or suffix -phosphate.

Amine

An organic compound containing an attached amino group ($-NH_2$), designated by the suffix -amine.