Chapter 2: Atoms, Ions, and Molecules Vocabulary

A set of vocabulary flashcards reviewing subatomic particles, chemical bonding, water properties, and pH concepts based on Chapter 2 lecture notes.

Matter

Anything that has mass and takes up space.

Proton

A subatomic particle with a positive charge and a mass of $1\text{ mass unit}$.

Neutron

A subatomic particle with a neutral charge and a mass of $1\text{ mass unit}$.

Electron

A subatomic particle with a negative charge and low mass that exists in principal energy levels surrounding the nucleus.

Atomic Number

The characteristic value of an element determined by the total number of protons in an atom.

Valence Shell

The outermost principal energy level shell surrounding the nucleus of an atom.

Valence Electrons

The electrons residing in the outermost shell that determine the chemical bonding properties of an element.

Ionic Bond

A chemical bond formed by electrostatic attraction between cations ($+$) and anions ($-$).

Covalent Bond

A chemical bond involving stable interactions between two atoms that share valence electrons.

Nonpolar Covalent Bond

A covalent bond in which electron density is shared equally around both atoms.

Polar Covalent Bond

A covalent bond in which electron density is higher around a particular atom, producing a dipole moment with partial charges.

Hydrogen Bond

A non-covalent interaction based on dipole-dipole attraction between a slightly positive hydrogen atom and a slightly negative atom such as oxygen, nitrogen, or fluorine.

Electrolytes

Inorganic salts or ions that conduct an electric current in solution when dissociated in water.

Hydrophilic

Refers to "water-loving" polar molecules and ions that dissolve in water.

Hydrophobic Exclusion

The process by which cohesive water molecules force out nonpolar ("water-fearing") molecules.

Amphipathic Molecules

Molecules containing both hydrophilic (polar) and hydrophobic (nonpolar) regions, such as phospholipids.

pH

A measure of the relative acidity or alkalinity of a solution, which is inversely proportional to the concentration of hydrogen ions ($[H^+]$).

Acid

A solute that acts as a proton donor, increasing the concentration of hydrogen ions ($[H^+]$) and lowering the pH of a solution.

Base

A solute that acts as a proton acceptor, decreasing the concentration of hydrogen ions ($[H^+]$) and raising the pH of a solution.

Buffer

A chemical agent or compound that resists changes in pH to preserve the stability of body fluids.

Alpha Helix and Beta Sheet

Secondary protein structures formed and held together by hydrogen bonds between polypeptide backbone chains.

pH Scale

A logarithmic scale ranging from $0$ to $14$ measuring hydrogen ion concentration, where pure water is $7.0$, blood is $7.35\text{ to }7.45$, and stomach acid is $2.0\text{ to }3.0$.