Biology: Chemical Structure and Properties of Water & Solutions

Vocabulary practice flashcards covering water's chemical structure, physical and chemical properties, solutions, and solubility concepts from biology lecture notes.

Polar Nature of Water

The property resulting from oxygen having a higher electronegativity than the two hydrogen atoms it shares electrons with, causing electrons to stay near oxygen and giving oxygen a negative charge while hydrogen has a positive charge.

VSEPR Theory (in Water)

The model explaining that because oxygen has two lone pairs of electrons, their strong repulsion forces the hydrogen-oxygen bonds downward to create a bent shape with a bond angle of $104.5^\circ$.

Cohesion

The tendency of water molecules to stick to each other due to hydrogen bonding.

Surface Tension

A phenomenon created because water molecules at the surface are pulled downward and to the side by cohesion, forming a film that allows organisms like water striders to stay on top.

Adhesion

The tendency of water to stick to other polar substances due to its polar properties.

Capillary Action

The process by which cohesion and adhesion enable water molecules to climb upward through narrow tubes, such as in trees and paper towel fibers.

Water Solubility

The ability of water to dissolve ionic compounds and polar molecules because the partial charges of oxygen and hydrogen attract positives and negatives to break compounds apart, aiding in transportation.

Low Density as a Solid

A unique property where hydrogen bonding between molecules and water's bent structure create more open space when frozen, causing ice to float and allowing aquatic life to survive underneath.

High Heat Capacity and Vaporization

The property where breaking hydrogen bonds requires large amounts of energy to change water from solid to liquid or liquid to gas; in humans, sweating utilizes this property as evaporating water removes excess thermal energy to prevent overheating.

Chemical Neutrality (Water)

The state of having a $\text{pH}$ of $7$, providing a neutral environment and perfect atomic balance.

Chemical Reactivity of Water

Water's capacity to act as an acid or base depending on the mixture, participate directly as a reactant in hydrolysis and dehydration synthesis, and govern enzyme activity with its $\text{pH}$ of $7$.

Intramolecular Force

Forces or chemical bonds that occur inside a single molecule.

Intermolecular Force

The attractive force that occurs between two separate molecules.

Solute

The substance that is dissolved in a solution.

Solvent

The substance that dissolves the solute.

Solution

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

Solvation

The process where solvent molecules surround and interact with solute particles to dissolve them.

Hydration

A specific type of solvation in which water acts as the primary solvent.

Hydration Shell

A cluster of water molecules that binds around a dissolved ion or molecule.

Dissociation

The process in which ionic compounds break apart into smaller ions when dissolved.

Agitation

The act of stirring a solution in order to increase the rate of dissolving.

Miscible

Liquids that can mix together to form a homogeneous solution, such as alcohol and water.

Immiscible

Liquids that cannot mix together and will separate into layers, such as oil and water.

Solubility

The maximum quantity of solute that can dissolve in a specified amount of solvent at a given temperature.

$$\text{g}/100\,\text{g}\ \text{H}_2\text{O}$$

The standard measurement unit for solubility representing the number of grams of solute that can dissolve in $100\,\text{g}$ of $\text{H}_2\text{O}$.

Saturated Solution

A solution that contains the maximum possible amount of dissolved solute such that no more solute can dissolve.

Unsaturated Solution

A solution containing less than the maximum capacity of solute, meaning it can still dissolve additional solute.

Hydrogen Bond Formation

The electrostatic attraction that occurs when a positively charged hydrogen atom forms an attraction with a negatively charged oxygen atom.