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Welcome to the Vocabulary Page of the Science Web.

To use this page simply click on the part of the alphabet below that you wish to view. You will be directed to the terms for that letter. In some cases you will be directed to other possible web sites that will give you more details about a term, person or theory.

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acid -  A substance that tastes sour, reacts with metals and carbonates, and turns blue litmus paper red.

acid rain - Rain with a pH less than 5.6; produced by substances in the air reacting with rainwater to make it acidic.

actinides - A group of elements in the second row of the rare earth elements in the periodic table.

alkali metal - An element in Group 1 of the periodic table.

alkaline earth metal - An element in group 2 of the periodic table.

amorphous solid - A solid made up of particles that are not arranged in a regular pattern

anhydrous - A chemical compound that normally has water molecules attached to its ions but from which the water has been removed.

Aqueous - Describes a solution made with water.

Archimedes Principle - The rule that the buoyant force on an object is equal to the weight of the fluid displaced by that object.

atom - The smallest particle of an element.

atomic mass - The average mass of one atom of an element.

atomic number - The number of protons in the nucleus of an atom.




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base - A substance that tastes bitter, feels slippery, and turns red litmus paper blue.

Bernoulli's Principle - The rule that a stream of fast moving fluid exerts less pressure than the surrounding fluid.

boiling - Vaporization that occurs on and below the surface of a liquid.

boiling point - The temperature at which a substance changes from a liquid to a gas.

Boyle's Law - The relationship between the pressure and volume of a gas at constant temperature; when volume increases, pressure decreases.

buoyant force -  The upward force exerted by a fluid on a submerged object.




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Celsius - A measurement scale used in SI to record temperature. 0 degrees = Freezing of water, 100 degrees = boiling point of water.

Change of state - The physical change of matter from one state to another.

Charles's Law - The relationship between the temperature and volume of a gas at constant pressure; when temperature increases, volume increases.

chemical change - A change in matter that produces new substances.

chemical equation - A short, easy way to show chemical reactions, using symbols instead of words.

chemical reaction -  A process in which substances undergo chemical changes.

chemical symbol - the shorthand or abbreviated way to write the name of a chemical element.

chemistry - The study of the properties of matter and how matter changes.

coefficient -  A number placed in front of a chemical formula in an equation that indicates how many atoms or molecules of each reactant and product are involved in a reaction.

colloid - A mixture with small undissolved particles that do not settle out.

compound - A substance made up of two more more elements chemically combined.

concentration -  Generally, the proportion of a solute dissolved in a solvent.

condensation - The change from the gaseous to the liquid state of matter

constant - In an experiment, a factor that doesn't change.

control - In an experiment, a standard for comparison that is often needed to draw meaningful conclusions.

covalent bond -  A type of chemical bond formed by atoms when they share electrons; covalent bonding produces molecules.

crystal - An orderly, three dimensional pattern of ions or atoms in a solid.

crystalline solid - A substance that is made up of crystals in which the particles are arranged in a regular, repeating pattern.




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decomposition reaction - A chemical reaction in which a substance breaks down (decomposes) into two or more simpler substances.

density - The measurement of how much mass of a substance is contained in a given volume. Density may be calculated by dividing the mass by the volume. Objects with a density greater than one will sink in water. Objects with a density less than one will float in water.

derived unit - Unit of measurement obtained by combing SI units; for example, density is a derived unit formed by dividing an object's mass by its volume.

dependent variable - In an experiment, the factor whose value changes because of a change in the independent variable.

dilute solution - A solution in which the amount of solute is much less that the maximum the solvent can hold at that temperature.

dissociation - The breaking apart of an ionic compound (such as salt) into positive and negative ions when dissolved in water.




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electron - Negatively charged particles that move around the nucleus of an atom.

element - A substance that cannot be broken down into other substances by chemical or physical means.

endothermic reaction - A chemical reaction in which energy is absorbed.

energy - The ability to cause change.

evaporation - The process that occurs when vaporization takes place only on the surface of a liquid.

exothermic reaction - A chemical reaction in which energy is released.

experiment - An organized procedure for testing a hypothesis. An experiment typically has a control and dependent and independent variables.




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fluid - Any material that flows; liquids and gases are fluids.

formula - A combination of symbols that shows the ratio of elements in a compound.

freezing - The change in state from a liquid to a solid.

freezing point - The temperature at which a substance changes from a liquid to a solid.




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gas - A state of matter with no definite shape or volume.

gram - a basic unit of mass in the metric system.

graph - A visual display of information or data organized to help people interpret, understand, or quickly find information.

group - In the periodic table, each of the 18 vertical columns of elements, each group (family) is made up of elements with similar properties.





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half-life - The amount of time required for one-half of the nuclides in a sample of radioactive isotope to decay.

halogen family - Highly active elements in periodic table Group 17 (fluorine, chlorine, bromine, iodine, astatine). Halogens have seven electrons in their outer energy shells and readily combine with Group 1 elements such as sodium.

heat - The movement of thermal energy from one substance to another.

Heat of Vaporization - The amount of energy needed to change a material from a liquid to a gas.

hydrogen ion - 

hydroxide ion -

hypothesis - A testable prediction used to see how something works or to solve a problem.




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independent variable - In an experiment, the factor adjusted to a different value by the experimenter to see what effect it will have on the dependent variable.

Inference - A logical interpretation based on observations and prior knowledge

ion - A positively or negatively charged atom.

ionic bond - A type of chemical bond formed by the attraction between opposite charges of the ions in the ionic compound.

isotope - Atoms of the same element that have different numbers of neautrons.




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Joule -  The basic unit of energy and work. 1 joule (j) = a force of i newton mving through i meter.



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Kelvin  - The SI unit of temperature; zero K = absolute zero (the coldest possible temperature, -273 C).

kilogram - The SI unit of mass; 1 kilogram

kinetic energy -  Energy that an object has because of its motion.

Kinetic theory of matter - The idea that all matter is made up of constantly moving, tiny particles.




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lanthanides - Any of the 14 metallic elements having atomic numbers 58 - 71; used in magnets, ceramics, and television picture tubes.

law of conservation of energy - A law stating that energy can change form but cannot be created or destroyed under ordinary conditions. This law applies to systems in which energy cannot enter or exit the system.

law of conservation of mass - A law stating that matter is neither created or destroyed during a chemical change.

liquid -  A state of matter that has a definite volume but no definite shape.

liter - The unit of liquid volume (L) that occupies the same volume as a cubic decimeter (dm3) and is slightly larger than a quart.





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malleable - Ability of metals to be hammered or rolled into thin sheets.

mass -  A measure of how much matter is in an object.

mass number - Sum of the number of protons and neutrons in an atom's nucleus.

melting - The change from a solid to the liquid state of matter.

melting point -  The temperature at which a substance changes from a solid to a liquid.

metalloid - Elements having properties of both metals and nonmetals.

meter - The SI base unit of length (m); 100 cm = 1 m.

mixture - Two or more substances that are mixed together but not chemically combined.

model - A symbolic representation of an idea, system, or structure to make something understandable. Models help us solve problems and deal with things difficult to see because they are too large or too small.

molecule - 





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neutralization -

neutron -

newton -

noble gas -

nonmetal -

nucleus -





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observation - Using your senses to gather information; in science we use instruments such as microscopes and balances to carefully gather accurate and detailed observations.





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Pascal's Principle - The rule that when force is applied to a confined fluid, the increase in pressure is transmitted equally to all parts of the fluid.

period -

periodic table -

pH scale -

physical change -  A change that alters the form or appearance of a substance but does not make the material into another substance.

plasma -  A state of matter in whic atoms are stripped of their electrons and the nuclei are packed closely together.

precipitate - A solid that forms from a solution during a chemical reaction.

pressure - The force exerted on a surface divided by the total area over which the force is exerted; also the force of a gas's outward push divided by the area of the walls of the container.

product -

proton -





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reactant -

replacement -





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salt -

saturated solution -

science - a study of the world around us.

scientific law - A rule that describes, but doesn't explain, a pattern in nature and predicts what will happen under specific conditions.

scientific theory - The most logical explanation of why things work the way they do. A theory is a former hypothesis that has been tested with repeated experiments and observations and found always to work.

second - The SI unit for time.

SI - International System of Units; standard, easy to use, worldwide system of measurement based on powers of ten. The SI standards are used by all scientists, and are the modern version of the metric system.

solid -  A state of matter that has a definite volume and a definite shape.

solubility -

solute -

solution -

solvent -

standard - In measurement, an exact quantity that everyone agrees to use as a basis for comparison.

states of matter - The forms that matter exists in (solid, liquid, gas and plasma)

sublimation -  The change in state from a solid directly to a gas without passing through the liquid state.

subscript -

supersaturated solution -

suspension -

symbol -  Usually one or two letter set of characters that is used to identify an element.

synthesis -





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technology - The practical use of scientific information to improve the quality of human life.

temperature -  The measure of the average kinetic energy of the particles in a substance.

theory - The most logical explanation of why things work the way they do. A theory is a former hypothesis that has been tested with repeated experiments and observations and found always to work.

thermal energy -  The total energy of a substance's particles due to their movement or vibration.

thermal expansion - The expansion of matter when it is heated.

time - The interval between two events; the SI unit for time is the second.

transition metal -

translucent -

transparent -





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unsaturated solution -





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valence electrons -

vaporization - The change from a liquid to the gaseous state of matter.

variable -  The part of an experiment that can be changed.

viscosity - The resistance of a liquid to flowing.

volume - The amount of space that matter occupies.





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weight -  A measure of the force of gravity on an object.





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