BIO 181 Lecture 2: The Chemical Foundations of Life

Flashcards covering vocabulary terms from Lecture 2 on the chemical foundations of life, including atomic structure, chemical bonds, water properties, pH, buffers, and organic compounds.

Chemistry

The scientific study of matter.

Matter

Anything that occupies space and has mass.

Atom

The fundamental unit of matter and the smallest unit of an element, composed of subatomic particles called protons, neutrons, and electrons.

Molecule

A structure formed when atoms bond together, where the unique order and arrangement of the atoms dictate its structure and function.

Atomic Number

The number of protons present in an atom's nucleus, which defines the identity of the atom.

Element

A basic pure substance that cannot be broken down and consists only of atoms with the same number of protons.

Atomic Weight (Mass)

The total number of protons plus neutrons in an atom's nucleus.

Bohr Model

An atomic model introduced by Niels Bohr and Ernest Rutherford in 1913 showing a central nucleus of protons and neutrons with electrons orbiting in circular energy shells at specific distances.

Free Radicals

Unstable atoms with vacancies in their outer energy shells that tend to interact with other atoms.

Ions

Electrically charged atoms formed when an atom loses or gains electrons.

Octet Rule

The principle stating that atoms are most stable when their outermost energy shells are completely filled with electrons.

Isotopes

Different forms of a single element consisting of atoms that have the same number of protons but different numbers of neutrons in their nuclei.

Radioactive Isotopes

Unstable isotopes with added neutrons that fall apart (decay) into atoms and release energy.

Half-life

The time required for half of a radioactive material's mass to decay into simpler forms.

Carbon Dating

A technique using Carbon-14 (which has a half-life of $5{,}730\text{ years}$) to estimate the age of organic materials, rocks, or plant matter.

PET Scan (Positron Emission Tomography)

A type of medical imaging test that uses radioactive tracers to form a digital image of interior body processes to look for disease.

Ionic Bond

A chemical bond involving the transfer of one or more electrons from one atom to another, forming charged ions that interact.

Covalent Bond

The strongest type of chemical bond, involving the sharing of a pair of electrons between atoms.

Electronegativity

The attraction of an atom's nucleus for the shared electrons within a covalent bond.

Polar Covalent Bond

A covalent bond in which shared electrons are pulled unequally between atoms.

Hydrogen Bond

A relatively weak interaction occurring when a partial positive charge on one molecule interacts with a partial negative charge on another molecule (commonly involving $\text{H}$ and $\text{O}$ or $\text{H}$ and $\text{N}$).

Cohesion

The tendency of water molecules to stick together due to hydrogen bonding between partial positive and negative charges.

Solute

The substance that is dissolved in a solvent to form a solution.

Solvent

The liquid substance capable of dissolving other substances to form a solution.

Solution

A homogeneous mixture formed when a solute dissolves in a solvent.

Hydrophilic

Describes "water-loving" molecules that possess partial or complete charges and dissolve readily in water.

Hydrophobic

Describes "water-fearing" molecules that do not possess charges and cannot dissolve in water.

Specific Heat

The amount of energy required to raise the temperature of a substance by $1^{\text{o}}\text{C}$.

pH Scale

A logarithmic scale ranging from acidic ($0$) to basic ($14$) that measures the concentration of hydrogen ions ($\text{H}^+$) in an aqueous solution.

Protonation

The addition of hydrogen ions ($\text{H}^+$) to biological molecules, which occurs in acidic environments containing excess $\text{H}^+$.

Deprotonation

The removal of hydrogen ions ($\text{H}^+$) from biological molecules, which occurs in basic environments containing low $\text{H}^+$ concentrations.

Buffer Solution

A solution used by living things to maintain pH at a nearly constant value by counteracting changes in hydrogen ion concentration.

Organic Molecules

Molecules composed primarily of carbon and hydrogen atoms.

Hydrocarbons

Organic compounds consisting entirely of carbon and hydrogen.

Functional Groups

Groups of atoms occurring within molecules that replace hydrogen and confer specific chemical properties and reactivity to those molecules.

Isomers

Molecules that share the same chemical formula but differ in the structure, placement, or chemical bonding of their atoms.

Enantiomers

Molecules that share the same chemical structure and bonds but differ in the three-dimensional placement of atoms so that they are mirror images.