Worlds of David Darling > Children's
Encyclopedia of Science > From Glasses to Gases > Glossary
FROM GLASSES TO GASES:
The Science of Matter
a book in the eXperiment! series by David Darling
Glossary
atom
There are 92 different kinds of atoms in nature. All substances are made
of atoms or of combinations of atoms called molecules.
density
The amount of matter, or mass, in a unit volume. Density measures how concentrated
a piece of matter is.
detergent
A cleaning substances. More detergents are continually being developed to
remove grease and dirt more effectively.
elasticity
A measure of the springiness of a material. A substance with high elasticity
can be stretched quite far and still return to its original shape.
insoluble
A substance is insoluble if it will not dissolve in a particular liquid.
A substance may be soluble in one liquid but insoluble in another.
matter
Anything that takes up space. This includes all solids, liquids, and gases.
metal fatigue
The weakness that may develop in a piece of metal that undergoes repeated
stretching or vibration. It begins when small cracks develop on the metal's
surface.
molecule
The smallest part of a substance that still has the chemical properties
of that substance. A molecule consists of atoms joined together.
plastic liquid
A liquid that will only flow when pushed or squeezed.
solubility
A measure of how well a substance dissolves in a particular liquid. The
solubility may be different in one liquid (e.g., water) than in another
(e.g., alcohol).
solution
A mixture of a liquid and one or more other substances. These other substances
may be solids, liquids, or gases.
solvent
The liquid in which a substance is dissolved.
state
The condition of a piece of matter – whether it is a solid, a liquid,
or a gas.
surface tension
The force acting across the surface of a liquid that makes the liquid seem
to have an elastic skin. It is caused by unbalanced forces between molecules
at the surface.
suspension
A liquid in which tiny solid particles hand without sinking to the bottom.
thixotrope
A liquid that thickens if left undisturbed but flows easily again if shaken
or stirred.
viscoelastic
A liquid that is both sticky (viscous) and springy (elastic) is viscoelastic.
viscosity
A measure of how well a liquid or a gas flows. A substance with a low viscosity
flows more easily than one with high viscosity.
viscous
A liquid or gas is called if viscous if it has a high viscosity. For example,
syrup and tar are viscous.
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