Visionlearning Glossary

A preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen’s structure that is used to stimulate immunity to a particular disease or antibody production.

Used in the following modules: DNA I

The number of single bonds an atom can form, also measured as the number of hydrogen atoms that typically bond to an atom of an element. For example, in H₂O, oxygen has a valence of two; in CH₄, carbon has a valence of four.

Used in the following modules: Chemical Bonding, Chemical Equations, Chemical Reactions, Nuclear Chemistry, Organic Chemistry, The Periodic Table of Elements

Electrons that can be actively involved in chemical change; usually electrons in the shell with the highest value of n (electrons in the "outermost" shell of an atom). For example, sodium's ground state electron configuration is 1s² 2s² 2p⁶ 3s¹; the 3s electron is the only valence electron in the atom. Valence electrons determine the chemical properties of an atom and are the only electrons that participate in chemical bonding.

Used in the following modules: Chemical Bonding, Chemical Reactions, Nuclear Chemistry, Organic Chemistry, The Periodic Table of Elements

The outermost electron shell of an atom that contains electrons.

Used in the following modules: Chemical Bonding, Chemical Equations, Chemical Reactions, The Periodic Table of Elements

To establish the soundness or truth of something, often using an independent means of checking results. Validation of data, models, statistical analyses, etc. is a key component of the process of science.

Used in the following modules: Data: Statistics, Research Methods: Modeling, Scientific Communication: Peer Review, Scientific Ethics

A general term for all attractive forces that occur between electrically neutral molecules. Van der Waals forces include dipole-to-dipole interactions, hydrogen bonds, and other intermolecular forces. For more information on the different types of van der Waals forces, visit "What are van der Waals forces?" at General Chemistry Online.

Used in the following modules: Matter: States of Matter

In science, the term refers to a condition or parameter that may be manipulated, fixed, measured, or observed in the course of scientific research. For more information, see: Research Methods: Experimentation

Used in the following modules: Data: Statistics, Data: Uncertainty, Error, and Confidence, Data: Using Graphs and Visual Data, Earth's Atmosphere, Research Methods: Comparison, Research Methods: Description, Research Methods: Experimentation, Research Methods: Modeling, Research Methods: The Practice of Science, Scientific Communication: Understanding Scientific Journals and Articles, Unit Conversion, Visionlearning

A small sac containing fluid and other material.

Used in the following modules: Absorption, Distribution and Storage of Chemicals

Small protrusions or bumps, usually on the surface of a membrane that increase its surface area.

Used in the following modules: Absorption, Distribution and Storage of Chemicals

English geophysicist, born in London (1939-). With his advisor, Drummond Matthews, Vine wrote “Magnetic Anomalies Over Ocean Ridges,” presenting ideas that helped the theory of plate tectonics gain widespread recognition and adherents. Vine also researched the history of Earth’s magnetic field and studied the electrical conductivity of the lower continental crust. For further information see work, The Foundation of Cellular Pathology on the Basis of a Physiological and Pathological Understanding of Tissue, formalizing the cell theory. For further information see Karl Virchow.