Chapter 1 Lesson One: Water, Hydrosphere, and Chemical Properties Vocabulary

Vocabulary flashcards covering key terms about water, its cycle, properties, and related Earth systems and processes from the lecture notes.

Water

A transparent liquid that allows chemical reactions, dissolves many substances, and exists in solid (ice), liquid (water), and gaseous (water vapor) states.

H2O

Chemical formula for water; composed of two hydrogen atoms covalently bonded to one oxygen atom.

Hydrogen

Lightest element; in water, one of the two elements forming the molecule H2.

Oxygen

Element that bonds with hydrogen to form water; makes up a large portion of water by mass.

Water molecule

A molecule of H2O with two covalent O–H bonds and a bond angle of about 104.5°.

Covalent bond

Bond formed by sharing electrons between atoms, as in the H–O bonds of water.

Bond angle (104.5°)

The angle between the two O–H bonds in a water molecule.

Polarity

Water’s polarity: partial negative charge on oxygen and partial positive charge on hydrogen due to electronegativity differences.

Electronegativity

Ability of an atom to attract electrons in a chemical bond; oxygen is more electronegative than hydrogen in water.

Hydrogen bond

Intermolecular attraction where a hydrogen atom bonds to a more electronegative atom in another molecule, crucial for water’s properties.

Boiling point

Temperature at which a liquid boils; for pure water under normal pressure, 100°C.

Evaporation

Liquid water turning into water vapor at any temperature.

Vaporization

Phase change from liquid to gas at the boiling point (distinguished from evaporation by occurring at the boiling point).

Condensation

Gas turning into liquid; formation of clouds from water vapor.

Melting

Phase change from solid to liquid (fusion).

Freezing

Phase change from liquid to solid (solidification).

Hydration

Process of surrounding ions with water molecules without breaking bonds.

Hydrolysis

Water participates in breaking bonds of solutes, forming ions; can alter acidity/basicity of solution.

Dissolution

Process by which a solute (e.g., NaCl) dissolves in a solvent, often producing hydrated ions.

Acid-base balance (pH)

Balance of hydrogen and hydroxide ions in solution; determines whether a solution is acidic, neutral, or basic.

Saltwater

Water with dissolved salts; primarily found in seas and oceans.

Freshwater

Water with low dissolved salts; found in rivers, lakes, and groundwater.

Cryosphere

Frozen portion of the hydrosphere, including polar ice, glaciers, and snow.

Atmosphere

Gaseous shell surrounding Earth.

Hydrosphere

All water on Earth, including oceans, rivers, lakes, and groundwater.

Lithosphere

Earth’s rigid outer layer, including crust and upper mantle.

Biosphere

Regions of Earth where living organisms exist.

Transpiration

Water loss from plants as water vapor.

Infiltration

Process by which water leaks from the surface into the soil and rocks, forming groundwater.

Groundwater

Water stored underground in soil or rock pores.

Water cycle (hydrologic cycle)

Nearly closed system where water moves through evaporation, condensation, precipitation, infiltration, runoff, and biological processes.

Hofmann voltmeter

A device used to measure gas volumes produced during electrolysis of water.

Electrolysis

Splitting of water into hydrogen and oxygen using electrical energy.

Hydrogen gas

Gas produced at the cathode during electrolysis of water.

Oxygen gas

Gas produced at the anode during electrolysis of water.