Chemical Context of Life and Water Properties Vocabulary

Vocabulary flashcards covering basic chemical bonds, properties of water, thermodynamics, pH scale, buffers, ocean acidification, and carbon chemistry strictly grounded in the lecture notes.

Polar Covalent Bond

A type of covalent bond where electrons are shared unequally between two atoms, creating regions of partial positive and partial negative charges, such as in $H_2O$.

Non-Polar Covalent Bond

A covalent bond in which electrons are shared equally between two atoms, resulting in no positive or negative regions, such as in $O_2$ and $H_2$.

Ionic Bond

A bond formed when a more electronegative atom steals electrons from a less electronegative atom, resulting in charged atoms or molecules called ions.

Cohesion

The linking together of water molecules to adjacent water molecules due to hydrogen bonding.

Adhesion

The clinging of one substance to a different substance, such as water molecules clinging to xylem tubes in plants or a glass surface.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid, which is exceptionally high in water due to cohesive hydrogen bonding.

Transpiration

The movement of water through a plant, entering in through the roots and exiting out through the stomata, enabled by cohesion and adhesion.

Kinetic Energy

The energy of motion; as atoms or molecules move faster, their kinetic energy increases.

Thermal Energy

The total kinetic energy associated with the random movement of atoms or molecules, which depends on the volume of matter.

Temperature

A measure of the average kinetic energy of the molecules in a body of matter, regardless of its volume.

Heat

The transfer of thermal energy from one body of matter to another, moving from a body of higher thermal energy to one of lower thermal energy.

Specific Heat

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

Evaporative Cooling

The process in which the surface of a liquid cools down as it evaporates, because the molecules with the highest kinetic energy escape as a gas.

Heat of Vaporization

The quantity of heat required to evaporate large amounts of liquid water into a gas.

Solvent

The dissolving agent in a solution, which is the substance in which solutes are dissolved.

Solute

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

Solution

A completely homogeneous liquid mixture composed of a solvent and one or more dissolved solutes.

Hydrophilic

Having an affinity for water (water-loving), often containing polar groups like hydroxyl groups ($-OH$) or charges that interact with water.

Hydrophobic

Having no affinity for water (water-fearing), consisting of non-polar and nonionic molecules, such as lipids, that repel water.

Hydronium Ion

The positively charged water molecule ($H_3O^+$) formed when a free hydrogen ion attaches to a water molecule.

Hydroxide Ion

The negatively charged ion ($OH^-$) left behind when a water molecule loses a hydrogen ion.

pH Scale

A logarithmic scale ($-\text{log}_{10}$) measuring the concentration of hydrogen ions ($H^+$) in a solution, where each unit change represents a $10\times$ difference in acidity.

Acid

A substance that increases the $H^+$ concentration of a solution, donating $H^+$ ions and resulting in a pH value less than $7$.

Base

A substance that reduces the $H^+$ concentration of a solution, accepting $H^+$ ions or releasing $OH^-$ ions, resulting in a pH value greater than $7$.

Buffer

A substance that minimizes changes in pH by accepting $H^+$ ions when they are in excess and donating $H^+$ ions when they are depleted.

Ocean Acidification

The process by which excess atmospheric $CO_2$ dissolves in ocean water, creating carbonic acid that dissociates into $H^+$ ions, reducing carbonate ions available for calcifying marine organisms.

Hydrocarbon Chains

Organic molecules consisting solely of carbon and hydrogen atoms, serving as non-polar carbon skeletons and energy sources such as fossil fuels.

Isomers

Compounds with the same chemical formula but different structural arrangements, shapes, or spatial orientations.

Functional Groups

Small characteristic clusters of atoms attached to a carbon skeleton that give organic compounds specific chemical properties and determine their reactions.