Visionlearning Glossary

Containing calcium.

To determine or check the accuracy of an instrument used for quantitative measurements, or to make corrections in or to adjust an aspect of a system.

The weak acid formed when CO₂ dissolves in water.

Used in the following modules: Acids and Bases, The Carbon Cycle

(also called Pistil) Female part of a flowering plant consisting of ovary with ovules and stigma/stamen structures to receive pollen.

Used in the following modules: Genetics I

The Cartesian plane, named after the mathematician Rene Descartes, is a plane with a rectangular coordinate system that associates each point in the plane with a unique pair of numbers in an ordered pair of the form (x,y). The x value is the horizontal coordinate and the y value is the vertical coordinate.

Used in the following modules: Wave Mathematics

A negatively charged terminal in an electrical cell.

Used in the following modules: Atomic Theory I, The Process of Science

A negatively charged beam of particles (electrons) that are emitted from the negative terminal in a vacuum tube.

Used in the following modules: The Process of Science

An ion that migrates to the cathode in an electrical cell; a positively charged ion.

Used in the following modules: Minerals III

English chemist and physicist born in Nice, France (1731-1810). Cavendish’s most important work was isolating hydrogen and describing its properties. He also researched electrical capacitance and used a torsion balance (now named for him) to measure the gravitational constant (G), which allowed him to calculate the mass of the Earth. For further information, see Henry Cavendish.

Used in the following modules: Gravity

An abbreviation for Common Era, which is a designation for the period of time beginning with year 1 of the Gregorian calendar. CE is an alternative to the abbreviation AD, and the numbering of years is identical to the Anno Domini system. Compare with BCE.

Used in the following modules: Data: Analysis and Interpretation, Research Methods: Experimentation, Research Methods: The Practice of Science, Scientific Communication: Utilizing the Scientific Literature

Swedish astronomer born in Uppsala (1701-1744). In 1742, Celsius invented the centigrade temperature scale, using the freezing and boiling points of water as his reference temperatures. Interestingly, he defined the freezing point as 100° and the boiling point as 0°. The scale was reversed to its present form after his death. Celsius also was the first to suggest that the aurora has a magnetic cause. For further information see atoms by bombarding them with alpha particles. He was awarded the Nobel Prize in physics in 1935 for his discovery of the neutron. For further information, see James Chadwick.

Used in the following modules: Atomic Theory I

British-American geophysicist and mathematician born in Eccles, Lancashire (1888-1970). In 1939, Chapman co-authored the classic work The Mathematical Theory of Non-Uniform Gases. The following year, he co-authored the two-volume work Geomagnetism. His most famous work in mathematics was his research in stochastic processes, for which he developed (independently of Andrey Kolmogorov) the Chapman-Kolmogorov equations. For further information see Sydney Chapman.

Used in the following modules: Earth's Atmosphere

A link between atoms. See ionic bond and covalent bond.

Used in the following modules: Chemical Bonding, Chemical Equations, Chemical Reactions

A process in which atoms and molecules recombine by forming or breaking chemical bonds. Chemical reactions form new products that have different chemical properties than the initial reacting material.

Used in the following modules: Chemical Equations, Chemical Reactions, DNA I, Fats and Proteins, Matter, Nuclear Chemistry, Research Methods: Modeling, Research Methods: The Practice of Science, The Rock Cycle

Compounds consisting of carbon, chlorine, fluorine, and sometimes hydrogen once used widely as aerosol propellants and refrigerants. The realization that chlorofluorocarbons cause depletion of the stratospheric ozone layer led to a sharp decrease in their use mandated by the Montreal Protocol in 1989.

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

The organized genetic structure of DNA with associated proteins that contains the hereditary information necessary for reproduction, protein manufacture, and other functions.

Used in the following modules: DNA I, Genetics I

The arranging of groups of organisms into sets or divisions on the basis of their evolutionary relationships.

Commonly referred to as burning, a chemical reaction between a fuel (for example wood) and an oxidizing agent (for example oxygen) that produces heat (and usually, light).

Used in the following modules: Organic Chemistry

A material formed by the chemical combination of elements in defined proportions. Compounds can be chemically decomposed into simpler substances.

Used in the following modules: Acids and Bases, Chemical Bonding, Chemical Reactions, Fats and Proteins, Matter, Minerals I, Minerals III, Research Methods: Experimentation, Research Methods: The Practice of Science, The Mole, The Nitrogen Cycle, Water

A type of breakage that produces a smooth, curved surface. Conchoidal fracture occurs when a substance has uniform strength in all directions and no pre-existing planes of atomic weakness. This generally occurs in two types of substances: minerals like quartz whose atomic structure consists of equally strong bonds in all directions, and volcanic glass, called obsidian, which has no definitive crystal structure.

The tendency to search for or interpret new information in a way that confirms one's preconceptions and avoid information and interpretations that contradict prior beliefs.

A curve formed by the intersection of a cone with a plane. This often results in a circle, ellipse or parabola. For more on conic sections, visit Mathworld's Conic Sections lesson.

Used in the following modules: Gravity

The uppermost layer of the earth that forms the continents. Unlike oceanic crust, continental crust is created and destroyed very slowly, so there is some continental crust on the earth as old as 4 billion years. Continental crust ranges from 10-70 km thick and is composed primarily of granite.

Used in the following modules: Earth Structure, Plate Tectonics II

The theory proposed in 1915 by Alfred Wegener, a German geophysicist and meteorologist. The theory stated that the continents had once been joined into one “supercontinent,” called Pangaea. About 200 million years ago, Pangaea broke apart and the continents drifted to their present positions. Wegener based his theory on the similarity of fossils and rock types on the east coast of South America and the west coast of Africa. The theory was widely ridiculed at the time because Wegener had not proposed a driving force for such drift. 

Used in the following modules: Plate Tectonics I, Plate Tectonics II

In science, a control is a system for which the expected change or outcome is well known and is measured or observed for the purpose of comparing it to a treatment group in scientific research. The control is used as a standard to compare or quantify change in the treatment. For more information, see: Research Methods: Experimentation

Used in the following modules: Adaptation, Charles Darwin II, Data: Statistics, Data: Uncertainty, Error, and Confidence, DNA I, Gravity, Research Methods: Comparison, Research Methods: Experimentation, Research Methods: Modeling, Scientific Communication: Peer Review, Scientific Communication: Understanding Scientific Journals and Articles, Scientific Ethics, Scientists and the Scientific Community, The Carbon Cycle, Using Science News in Teaching

The movement or circulation of a fluid due to variations in its density as a result of the transfer of heat within the fluid.

Used in the following modules: Earth Structure, Plate Tectonics II, The Rock Cycle

A plate boundary where two plates are moving towards each other.

American paleontologist, born near Philadelphia, Pennsylvania (1840-1897). Cope was a prolific writer and very successful fossil-hunter, publishing over 1200 papers during his career. He developed Cope’s law, stating that mammalian species become larger over time. Cope was especially interested in the natural history of reptiles and amphibians, publishing Bactrachian of North America and The Crocodilians and Snails of North America. Copeia, the leading scientific journal in the field of herpetology is named in his honor. For further information see Edward Drinker Cope.

Used in the following modules: Taxonomy II: Nomenclature

(Mikolaj Kopernik or Nicolaus Koppernigk) Polish astronomer born in Torun in the Royal Prussia region of the Kingdom of Poland (now Poland) (1473-1543). Copernicus was the first European scientist to provide scientific evidence for a heliocentric view of the solar system. In 1543, Copernicus published De revolutionibus orbium coelestium, often considered the origin of the Scientific Revolution. For further information see Nicolaus Copernicus

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

The innermost layer of the earth, which starts at ~2900 km depth. The core is composed mainly of iron and consists of a molten outer core and a solid inner core.

Used in the following modules: Atomic Theory I, Earth Structure, Educational Web Design, Research Methods: Comparison, Scientific Ethics, The Process of Science, Waves and Wave Motion

Correlation, as measured by the correlation coefficient, provides a measure of the strength and direction of a linear relationship between two random variables. While there are many measures of correlation, among the best known is the Pearson product-moment correlation, which ranges from -1 to 1. A correlation coefficient close to -1 indicates a strong negative correlation; a correlation coefficient close to 0 indicates little correlation; and a correlation coefficient close to 1 indicates a strong positive correlation.

Used in the following modules: Data: Statistics, Research Methods: The Practice of Science, Scientists and the Scientific Community, The Hydrologic Cycle

A metric unit of electrical charge equal to the charge on 6.24 × 10¹⁸ electrons.

A very strong chemical bond formed by the sharing of a pair of electrons. Multiple covalent bonds can be formed when multiple pairs of electrons are shared between atoms. Covalent bonds are generally characterized in two types, polar and non-polar covalent bonds. Compare to ionic bond, hydrogen bond.

Used in the following modules: Chemical Bonding

A molecule held together by covalent bonds, that is, pairs of electrons shared between atoms. Covalent molecules are true chemical molecules whose interaction with other molecules is influenced by whether a polar molecule or non-polar molecule is formed.

Used in the following modules: Chemical Bonding, Water

English molecular biologist, physicist, and neuroscientist, most noted for being one of the co-discoverers of the structure of the DNA molecule in 1953. He later contributed to the successful deciphering of the genetic code of DNA. For further information see Francis Crick

Used in the following modules: DNA II

The uppermost 5-70 km of the earth. There are two types of crust: continental and oceanic. Continental crust ranges from 10-70 km thick and has a composition approximating that of granite. Oceanic crust, on the other hand, is approximately 5 km thick and has a composition similar to basalt, making it significantly denser than continental crust.

Used in the following modules: Earth Structure, Minerals I, Minerals II, Minerals III, Plate Tectonics I, Plate Tectonics II, The Rock Cycle

A solid of defined shape that is bound by plane surfaces (facets) that intersect at characteristic angles. The shape of a crystal is defined by the bonding and/or interaction between atoms, ions, or molecules that make up the solid. The substances, planar angles and defects in a crystal affect the electrical and optical properties (including color) of the crystal.

Used in the following modules: Chemical Bonding, Matter: States of Matter, Minerals I, Minerals II, Minerals III, Plate Tectonics I, Research Methods: Description, The Rock Cycle, Water

The process through which crystals form, resulting in the change from a liquid or vapor to a solid. Crystallization can happen in two basic ways: 1. By lowering the temperature of a melted material like magma or water, atoms and ions start to aggregate into crystals, forming solid rock or ice. This can also happen from a vapor, as is the case with the formation of snowflakes, but it is much less common. 2. By evaporating water from a solution, the saturation point of the water is reached and a solid begins to precipitate out as crystals (for example, salt flats in the desert have been precipitated out of lakes that dried up).

French-Polish physicist and chemist born in Warsaw (1867-1934). Curie was the Head of the Physics Laboratory at the Sorbonne. Working with her husband, Pierre Curie, and inspired by Becquerel’s discovery of radiation, Curie isolated and named the element polonium. She also developed techniques for isolating radium from radioactive residues in order to study its properties. Curie was awarded, with Pierre, half a Nobel Prize in Physics in 1903, for their study of Becquerel radiation. After her husband’s death in 1906, she succeeded him as Professor of General Physics, and was the first woman to hold the post. In 1911 she was awarded a Nobel Prize in Chemistry for her work in radioactivity. For more information see Marie Curie.

Used in the following modules: Nuclear Chemistry

The French physicist born in Paris, France (1859 – 1906 CE). Pioneer in the fields of crystallography, magnetism, and piezoelectricity, he shared the 1903 Nobel Prize in Physics with his wife Marie Curie and with Henri Becquerel for research on the “radiation phenomena.” For further information see: Pierre Curie

The internal fluid of a cell (called cytosol) along with all dissolved materials and cellular organelles except for the nucleus. The cytoplasm is the primary site for chemical activity in the cell.

Used in the following modules: Cells