Polarity and Properties of Water

Vocabulary flashcards covering the chemical composition of life, covalent bonding, polarity, hydrogen bonding, solution chemistry, cohesion, adhesion, capillary action, high heat capacity, and ice density.

Major Elements in the Human Body

The four elements that make up $96.5\%$ of total human body weight: Oxygen ($65.0\%$), Carbon ($18.6\%$), Hydrogen ($9.7\%$), and Nitrogen ($3.2\%$).

Covalent Bond

A chemical bond formed when atoms share electrons, where each atom contributes one electron of each shared pair.

Polarity

The unequal distribution of electrical charge in a molecule, occurring when shared electrons spend more time near an atom with higher electronegativity.

Polar Covalent Compound

A compound in which shared electrons spend more time near the atom with higher electronegativity, creating an uneven distribution of charge.

Nonpolar Compound

A compound in which electrons are shared equally or arranged symmetrically, resulting in no net charge or electrical poles.

Hydrocarbon

A molecule containing only carbon and hydrogen atoms that is nonpolar due to a symmetrical arrangement of electrons and an even charge distribution.

Hydrogen Bonding in Water

An attraction formed when the weakly positive hydrogen atoms of one water molecule are attracted to the weakly negative oxygen atom of a neighboring water molecule.

Solvent

The substance in a solution that dissolves other materials, such as water dissolving polar or ionic substances.

Solute

The substance that is dissolved in a solvent to form a solution, such as sodium and chloride ions in water.

Dissociation

The complete separation or detachment of individual ions from each other when an ionic compound dissolves in water, such as $Na^+$ and $Cl^-$ detaching.

Hydrophilic

A 'water-loving' property of polar or ionic molecules that allows them to readily mix with or dissolve in water.

Hydrophobic

A 'water-fearing' property of nonpolar molecules that prevents them from mixing with water because water molecules are more attracted to each other.

Cohesion

The tendency of water molecules to stick to one another due to hydrogen bonding.

Surface Tension

A property of water caused by cohesion, where surface water molecules form stronger hydrogen bonds with neighboring surface molecules because they are not surrounded by water on all sides.

Adhesion

The property of water molecules tending to stick to other surfaces by forming hydrogen bonds with those surfaces.

Capillary Action

The phenomenon where cohesion and adhesion work together to draw water upward against gravity inside a narrow tube.

Transpiration

The evaporation of water from plant leaves into the air, which pulls replacement water upward through the plant.

Xylem

A system of narrow vessels in plants through which capillary action transports water from the roots to the leaves.

Specific Heat Capacity

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

High Heat Capacity of Water

The property of water requiring a large amount of heat energy to change its temperature, as energy first disrupts hydrogen bonds before increasing the kinetic energy of water molecules.

Water Content in Human Body Organs

The percentage of water comprising various body tissues, including Liver ($85\%$), Blood ($83\%$), Kidneys ($83\%$), Heart ($79\%$), Brain ($75\%$), Muscles ($75\%$), and Bones ($22\%$).

Density of Ice vs. Liquid Water

Ice is less dense than liquid water because stable hydrogen bonds hold water molecules in a fixed lattice, allowing ice to float on liquid water.

Winter Pond Temperature Stratification

The thermal layering of a pond in winter where ice forms at $0\,^\circ\text{C}$ on top, while the densest liquid water at $4\,^\circ\text{C}$ remains at the bottom to protect aquatic life.