Visionlearning Glossary

English physicist, chemist and meteorologist born in Eaglesfield, Cumberland (1766-1844). Dalton published Experimental Essays on the Constitution of Mixed Gases; on the Force of Steam or Vapour from water and other liquids in different temperatures, both in a Torricellian vacuum and in air; on Evaporation; and on the Expansion of Gasses by Heat, in which he details his theory of partial pressures in gas mixtures. He is most famous for his investigation of relative atomic weights, and for founding atomic theory. For further information see John Dalton.

Used in the following modules: Atomic Theory I, Earth's Atmosphere, Matter, Research Methods: Modeling

American geologist, mineralogist, and naturalist, born in Utica, New York (1813-1895). Dana published A System of Mineralogy in 1837, which remains a standard in the field. He served as geologist and mineralogist on the U.S. Antarctic and South Seas expedition in 1838-1842. On returning to the states, he published Zoophytes (1846), Geology (1849), and Crustacea (1852-55). He served as coeditor of the American Journal of Science. His other publications include Manual of Geology (1862), Manual of Mineralogy (1843), Corals and Coral Islands (1872), and Characteristics of Volcanoes (1890). For more information see James Dwight Dana.

Used in the following modules: Minerals II

English naturalist and geologist born in Shrewsbury, Shropshire (1809-1882). While serving as naturalist aboard HMS Beagle, Darwin developed his theory of evolution through natural selection based on his detailed observations of species, most famously, the variety of finches. He published his theory in 1859 in his book On the Origin of Species. His other works include The Descent of Man, and Selection in Relation to Sex and The Expression of the Emotions in Man and Animals. For further information, see Darwin Online.

Used in the following modules: Adaptation, Authoring Modules I, Charles Darwin I, Charles Darwin II, Research Methods: Comparison, Taxonomy I

(plural form of datum) A collection of pieces of information, generally taking the form of numbers, text, bits, or facts, that are related either by the method in which they are collected or the manner in which they are stored. For more information, see: Data: Analysis and Interpretation

Used in the following modules: Authoring Modules I, Bone Changes in Rock Climbers, Charles Darwin II, Data: Analysis and Interpretation, Data: Statistics, Data: Uncertainty, Error, and Confidence, Data: Using Graphs and Visual Data, Earth's Atmosphere, Genetics I, Plate Tectonics I, Plate Tectonics II, Research Methods: Comparison, Research Methods: Description, Research Methods: Experimentation, Research Methods: Modeling, Research Methods: The Practice of Science, Scientific Communication: Peer Review, Scientific Communication: Understanding Scientific Journals and Articles, Scientific Communication: Utilizing the Scientific Literature, Scientific Ethics, Scientific Institutions and Societies, Scientists and the Scientific Community, The Carbon Cycle, The Case of the Ivory-billed Woodpecker, The Process of Science, Using History and Biographies in Science, Visionlearning Teaching Modules

A material that is derived from the breakdown or division of another. For example, a product of the radioactive decay of an element; or a cell or cells that are derived from the division of a parent cell.

Used in the following modules: Charles Darwin II, Data: Uncertainty, Error, and Confidence, Nuclear Chemistry

In nuclear physics, the decay product of radioactivity.

Used in the following modules: Data: Uncertainty, Error, and Confidence

To break up into constituent parts by or as if by a chemical process, to rot.

Used in the following modules: Research Methods: The Practice of Science

Deltas form where rivers reach lakes, seas, or the ocean, and deposit their remaining sediment in a broad, flat plain as the river slows and eventually stops. The name comes from the Greek letter delta, shaped like a triangle, as these features are often triangular with one point at the river mouth.

Used in the following modules: Research Methods: Modeling, The Rock Cycle

Greek natural philosopher born in Thrace (ca. 460-370 BCE). With his teacher, Leucippus, Democritus developed the atomist concept of the cosmos, which held that the world is composed of invisible, minute particles suspended in a void. For further information, see Democritus.

Used in the following modules: Light I, Matter

The loss or removal of nitrogen or nitrogen compounds; specifically: reduction of nitrates or nitrites commonly by bacteria (as in soil) that usually results in the escape of nitrogen into the air.

Used in the following modules: The Nitrogen Cycle

A measure of the compactness of a substance given by the mass per unit volume (d = m/v). Common units of density include g/ml, g/cm³, and kg/L. A measure of lead is not heavier than an equivalent measure of styrofoam, it is denser.

Used in the following modules: Density, Earth Structure, Earth's Atmosphere, Matter: States of Matter, Minerals I, Minerals II, Research Methods: Modeling

A double-stranded, helical polymer of the sugar deoxyribose, phosphate, and one of four nucleotide bases (Adenine, Cytosine, Guanine, and Thymine). The molecule is the primary carrier of genetic information in all cells.

In science, a dependent variable refers to a condition or parameter that may change as a result of an experimental treatment on an independent variable. The change in the dependent variable is then observed or measured toward understanding the underlying processes involved in the change. For more information, see: Research Methods: Experimentation

Used in the following modules: Research Methods: Experimentation

French mathematician and philosopher born in Indre-et-Loire, France (1596-1650). Descartes invented analytical geometry and developed what is now called the Cartesian coordinate system, which describes geometry in term of algebra. He was an influential philosopher as well, famously stating, “Cogito ergo sum” (I think therefore I am). For further information see Rene Descartes.

Used in the following modules: Light I, Wave Mathematics

The isotopic labeling of a compound that contains hydrogen through the substitution of deuterium for some or all of the hydrogen in the molecule.

Used in the following modules: Scientific Ethics

A stable isotope of hydrogen (written ²H) that contains one neutron in its nucleus and has a natural abundance of 0.015%.

Used in the following modules: Atomic Theory II, Scientific Ethics

A molecule that contains two atoms. All of the non-inert gases occur as diatomic molecules: H₂, O₂, N₂, F₂, and Cl₂.

Used in the following modules: Chemical Equations

An equation relating a variable that changes over time (referred to as a function), to its rate of change (referred to as its derivative). Many fundamental relationships in the natural world are described by differential equations, for example Newton’s Second Law relates the force on a particle to the rate of change of that particle’s linear momentum: F = d (mv) / dt. In this equation, the force on a particle (F) is equal to the rate of change over time (expressed by the derivative designation d / dt) of the particle’s momentum (which is a product of the particle’s mass [m] and velocity [v]).

Used in the following modules: Research Methods: Modeling

To undergo the process of diffraction.

Used in the following modules: Light I

The bending or spreading of waves when they meet an obstruction.

Used in the following modules: DNA II, Light I, Minerals I, Minerals III, Research Methods: Description

The movement of atoms or molecules from one part of a medium to another caused by their random thermal motion. The result of diffusion is a tendency for particles to move from an area of higher concentration to an area of lower concentration.

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

An intrusive igneous rock of intermediate composition, often called “salt-and-pepper” rock because of its speckled black and white appearance. The main minerals present are plagioclase and hornblende. Around the world, diorite forms below volcanoes along convergent boundaries, and its extrusive equivalent is andesite.

Used in the following modules: The Rock Cycle

An asymmetrical distribution of electrical charge across an object. Polar molecules contain a dipole.

Used in the following modules: Chemical Bonding, Water

An interaction between two or more molecular dipoles resulting from the attraction between oppositely charged ends of the molecules.

The breaking apart of a molecule, especially in the presence of heat or a polar solvent. For example, the ionic compound sodium chloride dissociates in water by separating into positively charged sodium ions and negatively charged chlorine atoms.

A plate boundary where two plates are moving away from each other.

Deoxyribonucleic Acid. A double-stranded nucleic acid containing the sugar 2-deoxy-D-ribose. A constituent of cellular nuclear material responsible for encoding genetic information in most organisms. Specifically, a template for the synthesis of proteins and enzymes in most organisms.

Used in the following modules: DNA I, DNA II, Genetics I, Research Methods: Comparison, Research Methods: Description, Research Methods: The Practice of Science, Scientists and the Scientific Community, The Nitrogen Cycle, The Process of Science