Chemistry of Life and Organic Molecules

Vocabulary flashcards covering foundational chemical concepts, properties of water, pH and buffers, organic carbon chemistry, isomers, functional groups, and macromolecular structures from the lecture notes.

Isotope

An atomic form of an element with a specific number of neutrons.

Radioactive Isotope

An isotope whose nucleus spontaneously decays more than others.

Half-life

The time it takes for $50\%$ of a sample of an isotope to radioactively decay.

Carbon Dating

A method where scientists measure the ratio of radioactive C-14 to C-12 to calculate how many half-lives (in years) have passed since an organism was fossilized.

Orbital

The 3-D space an electron is in $90\%$ of the time.

Covalent Bonds

Strong bonds that involve sharing electrons between atoms.

Molecule

Two or more atoms held together by a covalent bond.

Compound

A substance made of two or more atoms of different elements bonded together.

Electronegativity

The relative ability of an atom to attract shared electrons to itself when bonded to another atom.

Nonpolar Molecules

Molecules that share electrons equally between atoms.

Polar Covalent Molecules

Molecules that share electrons unequally between atoms.

Ionic Bonds

Strong bonds formed by a two-step process: first, electron transfer between atoms, and second, the attraction of opposite charges.

Cation

A positively charged ion.

Anion

A negatively charged ion.

Hydrogen Bonding

Weak attraction occurring when hydrogen in polar covalent bonds with highly electronegative atoms (O or N) gets a slight positive charge and is attracted to negatively charged atoms.

Van der Waals Interactions

Weak interactions occurring when a nonpolar molecule's random accumulation of electrons in one region creates a slight negative charge, attracting to slightly positively charged molecules.

Chemical Reaction Equilibrium

The condition where reversible chemical reactions occur at the same rate in opposite directions.

Emergent Properties of Water

Four essential properties of water: Cohesive & Adhesive Behavior, Ability to Moderate Temp, Expansion upon Freezing, and Versatility as a Solvent.

Cohesion

Hydrogen bonds that develop between water molecules.

Adhesion

Hydrogen bonds that develop between water molecules and other substances.

Kinetic Energy

The energy of motion.

Thermal Energy

The kinetic energy associated with the random movement of molecules.

Temperature

A measure of thermal energy, representing the average kinetic energy of the molecules in a substance.

Heat

Thermal energy that is transferred from one place to another.

Specific Heat

The amount of heat that must be absorbed or lost for $1\,g$ of a substance to change its temperature by $1^\circ\text{C}$.

Heat of Vaporization

The quantity of heat a liquid must absorb to be converted into a gas.

Evaporative Cooling

Cooling that occurs because the hottest molecules are the most likely to leave as gas during vaporization.

Hydrophilic

Property describing polar substances that interact favorably with water.

Hydrophobic

Property describing nonpolar substances that do not interact with water.

pH Scale

A scale used to measure the acidity of an aqueous solution based on $\text{H}^+$ and $\text{OH}^-$ ion concentrations.

Acids

Substances that donate $\text{H}^+$ in aqueous solutions, creating a solution with a pH of less than $7$.

Bases

Substances that donate $\text{OH}^-$ or accept $\text{H}^+$ in aqueous solutions, creating a solution with a pH greater than $7$.

Buffer

A substance that minimizes change in $[\text{H}^+]$ and $[\text{OH}^-]$ by accepting $\text{H}^+$ when in excess and donating $\text{H}^+$ when $[\text{H}^+]$ drops.

Carbonic Acid

An acid that acts as an acidity buffer in human blood to protect sensitive proteins from harm.

Organic Molecules

Molecules containing carbon, which has a valence of $4$ and can form diverse structures by covalent bonding with one to four other atoms.

Hydrocarbons

Compounds consisting of only the elements carbon and hydrogen, found in fossil fuels and decayed ancient organisms.

Isomers

Compounds with the same number of atoms of elements but different structures and properties.

Structural Isomers

Isomers that differ in the covalent arrangement of their atoms.

Cis-trans Isomers

Isomers that differ in spatial arrangements around double bonds.

Enantiomers

Isomers that differ in spatial arrangement around an asymmetric carbon atom.

Functional Group

A chemical group directly involved in chemical reactions.

Phosphate Group

An important functional chemical group found in ATP.

Polymers

Chain-like macromolecules made of repeating monomers; includes carbohydrates, proteins, and nucleic acids.

Lipids

The fourth major class of organic macromolecules, which is not a polymer.

Dehydration Reaction

A chemical reaction that joins monomers together to form polymers.

Hydrolysis Reaction

A chemical reaction that disassembles polymers into monomers.

Carbohydrates

A class of macromolecules that serve as fuel and building materials for organisms.

Monosaccharide

A single simple sugar molecule that serves as the monomer for carbohydrates.

Disaccharide

A molecule consisting of $2$ simple sugars joined by a covalent bond.

Polysaccharide

A carbohydrate polymer composed of hundreds to thousands of simple sugars bonded together covalently.