Chapter 2: The Chemical Basis of Life - Water & Carbon

Vocabulary flashcards generated from lecture notes covering fundamental chemical principles, water properties, energy forms, and functional groups.

Proton

A positively (+) charged subatomic particle located in the nucleus of an atom.

Neutron

A neutral subatomic particle located in the nucleus of an atom.

Electron

A negatively (–) charged subatomic particle found in orbitals surrounding the nucleus.

Atomic number

The characteristic number of protons in the nucleus of an atom, which determines its chemical properties and element identity.

Isotope

A form of an element that possesses a different number of neutrons than other forms of the same element.

Mass number

The total number of protons plus neutrons in the most common isotope of an element.

Valence

The number of unpaired electrons in an atom's outermost electron shell.

Covalent bond

A chemical bond formed when unpaired valence electrons from two atoms are shared by both nuclei to fill their orbitals.

Ionic bond

A chemical bond formed by the complete transfer of electrons from one atom to another, resulting in an attraction between oppositely charged ions.

Nonpolar covalent bond

A covalent bond in which electrons are shared equally between two atoms with equal electronegativity, resulting in no charge on the atoms.

Polar covalent bond

A covalent bond in which electrons are shared unequally because one atom is more electronegative, creating partial negative ($\delta^-$) and partial positive ($\delta^+$) charges.

Ion

An atom or molecule that carries a full electrical charge.

Cation

A positively charged ion formed when an atom loses an electron.

Anion

A negatively charged ion formed when an atom gains an electron.

Electronegativity

The relative ability of an atom to attract shared electrons, which increases with a higher number of protons and decreases with increased electron shielding (ordered as $O > N > C = H$).

Hydrophilic

Referring to polar molecules or ions that interact readily with water's partial charges and remain in solution.

Hydrophobic

Referring to uncharged, nonpolar compounds that do not dissolve in water.

Cohesion

The binding attraction between like molecules, such as water molecules binding to each other via hydrogen bonds to produce high surface tension.

Adhesion

The binding attraction between unlike molecules, such as water adhering to plastic, glass, or epithelial surfaces.

Chemical evolution theory

The hypothesis that simple chemical compounds in Earth's early history combined to form more complex carbon-containing molecules prior to the origin of life.

Chemical equilibrium

The state of a reaction in which the forward and reverse reactions proceed at the same rate, keeping the concentrations of reactants and products constant.

Endothermic reaction

A chemical reaction that must absorb heat from its surroundings to proceed.

Exothermic reaction

A chemical reaction that releases heat into its surroundings.

Potential energy

Stored energy that exists based on an object's position or molecular structure.

Kinetic energy

The energy of active motion.

Chemical energy

A form of potential energy stored within the chemical bonds of a molecule.

Amino group

A functional group ($\text{-NH}_2$) that acts as a base by attracting a proton in solution to form $\text{-NH}_3^+$.

Carboxyl group

A functional group ($\text{-COOH}$) that acts as an acid by losing a proton in solution.

Carbonyl group

A functional group containing a carbon double-bonded to an oxygen ($\text{C=O}$), present in aldehydes and ketones, which reacts with compounds to form larger molecules.

Hydroxyl group

A highly polar functional group ($\text{-OH}$) that enhances compound solubility in water through hydrogen bonding and can act as a weak acid.

Phosphate group

A functional group that stores large amounts of chemical energy when multiple units are linked together.

Sulfhydryl group

A functional group ($\text{-SH}$) found in thiols that can form disulfide ($\text{S-S}$) bonds to contribute to protein structure.