What is water?
Water has no color, no odor, and no taste and is not heavy or light, having a density almost the same as our bodies. Water is a liquid earth material and plays a central role in sculpting the planet’s surface and in causing and moderating Earth’s weather and climate. It is a molecule composed of two atoms of hydrogen and one atom of oxygen (H2O).
Water covers nearly ¾ of earth’s surface and is still the most precious substance on Earth. The oceans contain 97% of Earth’s water supply.
Vocabulary and definitions for Unit on Water
Algae: any of a large group of mostly aquatic organisms that contain the green pigment chlorophyll but lack veins.
Condensation: the process by which water vapor changes into liquid water, usually on a surface.
Cycle: a process or action that repeats itself in the same order over time.
Dissolve: to break down into particles so small when mixed with water that a substance seems to disappear.
Evaporation: the process by which liquid water changes into water vapor.
Flash flood: a sudden flow of water over the land. Flash floods usually occur within a few minutes or hours of excessive rainfall.
Freeze: to change from a liquid to a solid state as a result of cooling.
Gas: a state of a substance with no definite shape or volume.
Glacier: a large mass of ice moving slowly over land.
Gravity: the natural force that pulls objects toward each other. On Earth, all objects are pulled toward the center of the Earth.
Ice: the solid state of water.
Iceberg: a large mass of ice that has become detached from a glacier and floats in the ocean.
Liquid: a state of a substance with no definite shape but a definite volume.
Matter: anything that has mass.
Melt: to change from a solid to a liquid state as a result of warming.
Molecule: the smallest part of a substance that is made up of two or more atoms.
Slope: a slanted or tilted surface.
Solid: a state of a substance with a definite shape and volume.
Storm surge: water pushed ahead of a storm like snow before a shovel. Water piles up along a coast, rushing toward land faster than it can return to the sea.
Surface tension: the skinlike surface on water (and other liquids) that pulls it together into the smallest possible volume (sphere).
Water: a liquid earth material made of hydrogen and oxygen.
Water quality: a term used to describe the purity of water.
Water vapor: the gaseous state of water.