[person] 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.

• Appears in modules:

• Atomic Theory I
• Atomic Theory II
• Chemical Equations
• Chemical Reactions
• Composition of Earth's Atmosphere
• Early Ideas about Matter
• History of Earth's Atmosphere I
• Kinetic-Molecular Theory
• Modeling in Scientific Research
• Properties of Gases
• Thermodynamics I

[person] 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).

• Appears in modules:

• Properties of Minerals

[person] 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.

• Appears in modules:

• Adaptation
• Barbara McClintock
• Charles Darwin I
• Charles Darwin II
• Charles Darwin III
• Comparison in Scientific Research
• Future of Human Evolution
• Mendel and Independent Assortment
• Population Genetics
• Scientists and the Scientific Community
• Taxonomy I
• The Piltdown Hoax
• Theories, Hypotheses, and Laws

[noun - data] (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 our module Data Analysis and Interpretation.

• Appears in modules:

• Atomic Theory II
• Atomic Theory III
• Barbara McClintock
• Bernardo Houssay
• Biodiversity I
• Bone Changes in Rock Climbers
• Cellular Organelles I
• Charles Darwin II
• Comparison in Scientific Research
• Composition of Earth's Atmosphere
• Confidence Intervals
• Craig Lee
• Creativity in Science
• Data Analysis and Interpretation
• Description in Scientific Research
• Ellen Ochoa
• Energy
• Experimentation in Scientific Research
• Exponential Equations in Science I
• Factors that Control Regional Climate
• France Anne-Dominic Córdova
• Introduction to Descriptive Statistics
• Introduction to Inferential Statistics
• Kevin Arrigo
• Kinetic-Molecular Theory
• Linear Equations in Science
• Mario Molina
• Measurement
• Mendel and Inheritance
• Meselson and Stahl
• Modeling in Scientific Research
• Origins of Plate Tectonic Theory
• Peer Review in Scientific Publishing
• Plates, Plate Boundaries, and Driving Forces
• Properties of Gases
• Santiago Ramón y Cajal and Camillo Golgi
• Scientific Controversy
• Scientific Ethics
• Scientific Institutions and Societies
• Scientists and the Scientific Community
• Sergio Avila
• Statistics in Science
• Taxonomy I
• The Carbon Cycle
• The Case of the Ivory-billed Woodpecker
• The How and Why of Scientific Meetings
• The Nature of Scientific Knowledge
• The Phosphorus Cycle
• The Piltdown Hoax
• The Practice of Science
• The Process of Science
• The Scientific Method
• Theories, Hypotheses, and Laws
• Uncertainty, Error, and Confidence
• Understanding Scientific Journals and Articles
• Using Graphs and Visual Data in Science
• Utilizing the Scientific Literature
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - data] A collection of measurements and observations that can be analyzed.

• Appears in modules:

• Confidence Intervals
• Data Analysis and Interpretation
• Ellen Ochoa
• Introduction to Descriptive Statistics
• Introduction to Inferential Statistics
• Sergio Avila
• Statistics in Science
• Uncertainty, Error, and Confidence

[noun - cells, atoms & subatomic particles] 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.

• Appears in modules:

• Cell Division I
• Cell Division II
• Cellular Organelles I
• Charles Darwin II
• David Ho
• Discovery and Structure of Cells
• Meselson and Stahl
• Nuclear Chemistry
• Origins of Life II
• Uncertainty, Error, and Confidence

[noun - atoms & subatomic particles, energy, atoms & subatomic particles, energy, modern physics] An experiment carried out in the 1920’s by American physicists Clinton Davisson and Lester Germer, it produced data that confirmed de Broglie’s hypothesis of electrons having wave-like character.

• Appears in modules:

• Atomic Theory III

[noun - atoms & subatomic particles, energy, matter, atoms & subatomic particles, energy, matter, modern physics] the wavelength (λ) associated with a fundamental particle, that is related to Planck’s constant (h) and momentum (ρ), via the equation, λ= h/ρ .

• Appears in modules:

• Atomic Theory III

[person - atoms & subatomic particles, energy, atoms & subatomic particles, matter, modern physics] French physicist whose PhD thesis first suggested the wave nature of electrons, leading to the establishment of wave-particle duality in quantum theory. Won the 1929 Nobel Prize in physics for "his discovery of the wave-nature of electrons."

• Appears in modules:

• Atomic Theory III

[person] Dutch botanist and geneticist, born in Haarlem, Holland (1848-1935). He is known for "rediscovering" Gregor Mendel's 1850s laws of heredity in the 1890s. Based in part on that rediscovery, he suggested the concept of genes, and developing a theory of evolution based on mutations.

• Appears in modules:

• Mendel and Independent Assortment

[noun - science & decision making, science communication] A reasoned discussion of opposing points in an argument.

• Appears in modules:

• Atomic Theory III
• Biodiversity I
• Carlos J. Finlay
• Cellular Organelles I
• Comparison in Scientific Research
• Data Analysis and Interpretation
• DNA II
• Experimentation in Scientific Research
• France Anne-Dominic Córdova
• Gravity
• History of Earth's Atmosphere II
• Membranes I
• Peer Review in Scientific Publishing
• Plates, Plate Boundaries, and Driving Forces
• Scientific Controversy
• Solutions, Solubility, and Colligative Properties
• The Phosphorus Cycle
• The Piltdown Hoax
• The Practice of Science
• The Process of Science
• Theories, Hypotheses, and Laws
• Water

[verb] To break down; to decrease over time in size, amount, or force.

• Appears in modules:

• Atomic Theory II
• Energy
• Exponential Equations in Science I
• Exponential Equations in Science II
• History of Earth's Atmosphere II
• Nuclear Chemistry
• The Nitrogen Cycle
• The Rock Cycle
• Uncertainty, Error, and Confidence

[verb] To break up into constituent parts by or as if by a chemical process; to rot.

• Appears in modules:

• History of Earth's Atmosphere II
• Mario Molina

[noun - units of measurement, geometry] [temperature] One graduated unit of measure on a Fahrenheit or Celsius temperature scale. On the Kelvin scale, graduations are called Kelvins.

[geometry] A measure of an angle. A full circle consists of 360 degrees.

• Appears in modules:

• Biodiversity I
• Composition of Earth's Atmosphere
• Earth Structure
• Energy
• Factors that Control Earth's Temperature
• Linear Equations in Science
• Mario Molina
• States of Matter
• Temperature
• The Carbon Cycle
• The Silicate Minerals
• Wave Mathematics

[noun] 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.

• Appears in modules:

• Linear Equations in Science
• Modeling in Scientific Research
• The Rock Cycle

[person] 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.

• Appears in modules:

• Atomic Theory I
• Early Ideas about Matter
• Light I
• Properties of Gases

[verb - chemical reactions, organic & biochemistry, rock cycle] 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.

• Appears in modules:

• The Nitrogen Cycle

[adjective - matter] Compact, packed close together; having a high mass in relation to volume.

• Appears in modules:

• Atomic Theory I
• Atomic Theory II
• Density
• Earth Structure
• Factors that Control Regional Climate
• Lipids
• Meselson and Stahl
• Plates, Plate Boundaries, and Driving Forces
• Properties of Liquids
• Properties of Solids
• Scientists and the Scientific Community
• States of Matter
• The Rock Cycle
• The Silicate Minerals
• Water

[noun - units of measurement, matter] 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.

• Appears in modules:

• Atomic Theory I
• Atomic Theory IV
• Cell Division II
• Composition of Earth's Atmosphere
• Confidence Intervals
• Defining Minerals
• Density
• Diffusion I
• Earth Structure
• Ellen Ochoa
• Meselson and Stahl
• Modeling in Scientific Research
• Properties of Minerals
• Properties of Solids
• States of Matter

[noun] 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.

[noun - research methods] 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 our module Experimentation in Scientific Research.

• Appears in modules:

• Experimentation in Scientific Research
• Exponential Equations in Science I
• Introduction to Inferential Statistics

[person - research methods, science & decision making, scientific concepts] 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).

• Appears in modules:

• Exponential Equations in Science I
• Light I
• Linear Equations in Science
• Scientific Notation and Order of Magnitude
• Wave Mathematics

[noun - evolution & adaptation] Ancestry or heritage.

• Appears in modules:

• Charles Darwin I
• Charles Darwin III
• Comparison in Scientific Research
• Discovery and Structure of Cells
• Theories, Hypotheses, and Laws
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - statistics] A set of statistical measurements, and the practice of using them, to quantitatively describe the main features of a dataset or population. Descriptive statistics allow a scientist to quickly and concisely summarize the central tendency and spread, or variability, of a data set. These measurements commonly include the mean, median, and standard deviation, but can also include graphical representations of a dataset.

• Appears in modules:

• Introduction to Descriptive Statistics
• Introduction to Inferential Statistics

[adjective - chemical reactions, compounds, physical & chemical properties] The isotopic labeling of a compound that contains hydrogen through the substitution of deuterium for some or all of the hydrogen in the molecule.

• Appears in modules:

• Scientific Ethics

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

• Appears in modules:

• Scientific Ethics

[adjective - atoms & subatomic particles, compounds, physical & chemical properties] A molecule that contains two atoms. All of the non-inert gases occur as diatomic molecules: H₂, O₂, N₂, F₂, and Cl₂.

• Appears in modules:

• Chemical Bonding

[noun - 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]).

• Appears in modules:

• Atomic Theory III
• Modeling in Scientific Research

[verb - atoms & subatomic particles, light & optics, mechanics] To undergo the process of diffraction.

• Appears in modules:

• Creativity in Science
• Light I

[noun - atoms & subatomic particles, light & optics, mechanics] The bending or spreading of waves when they meet an obstruction.

• Appears in modules:

• Atomic Theory III
• Creativity in Science
• Defining Minerals
• Description in Scientific Research
• DNA II
• Light I
• The Silicate Minerals

[noun - anatomy & physiology, toxicology & pharmacology, physical & chemical properties, biomolecules, atoms & subatomic particles, matter, atoms & subatomic particles, matter] 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.

• Appears in modules:

• Absorption, Distribution, and Storage of Chemicals
• Atomic Theory I
• Diffusion I
• France Anne-Dominic Córdova
• Kinetic-Molecular Theory
• Lipids
• Mario Molina
• Membranes I
• Membranes II
• Origins of Life I
• Origins of Life II
• Understanding Scientific Journals and Articles
• Using Graphs and Visual Data in Science

[noun - anatomy & physiology, toxicology & pharmacology, atoms & subatomic particles, matter, physical & chemical properties, atoms & subatomic particles, matter] Developed by Adolf Fick, a mathematical framework stating that the diffusion rate of a substance is proportional to the difference in concentration between the two areas. This means that, if the concentration of a given substance is high in relation to the substance it is diffusing into (e.g., food coloring into water), the process will be faster than if the concentration difference is low (e.g., food coloring into food coloring).

• Appears in modules:

• Diffusion I

[noun - equations] A method for converting between units of measurement.

• Appears in modules:

• Unit Conversion

[noun - rocks & minerals] 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.

• Appears in modules:

• The Rock Cycle

[noun - atoms & subatomic particles, physical & chemical properties] An asymmetrical distribution of electrical charge across an object. Polar molecules contain a dipole.

• Appears in modules:

• Chemical Bonding
• Properties of Liquids

[noun - atoms & subatomic particles, elements, physical & chemical properties] An interaction between two or more molecular dipoles resulting from the attraction between oppositely charged ends of the molecules.

• Appears in modules:

• Properties of Liquids

[noun - atoms & subatomic particles, matter] An interaction between a dipole and an induced dipole resulting from the attraction between opposite charges in the dipole and the resulting induced dipole.

• Appears in modules:

• Properties of Liquids

[verb - atoms & subatomic particles, chemical reactions] 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.

[noun - hydrology & fresh water, oceanography, rock cycle, natural resources, nutrient cycles] Organic and inorganic substances that have dissolved into a volume of water. Dissolved solids include salts, minerals, and other materials that are not water.

• Appears in modules:

• The Phosphorus Cycle

[noun - physical & chemical properties] the physical process of purifying a liquid by evaporation and condensation. For example, saltwater can be distilled to separate salt molecules from water molecules

[noun - seismology & plate tectonics] A plate boundary where two plates are moving away from each other.

• Appears in modules:

• Plates, Plate Boundaries, and Driving Forces

[noun - cells, genetics & inheritance] 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.

• Appears in modules:

• Barbara McClintock
• Biodiversity I
• Cell Division I
• Cell Division II
• Cellular Organelles I
• César Milstein
• Comparison in Scientific Research
• Creativity in Science
• David Ho
• Description in Scientific Research
• Discovery and Structure of Cells
• DNA I
• DNA II
• DNA III
• Gene Expression
• Linear Equations in Science
• Membranes II
• Mendel and Independent Assortment
• Mendel and Inheritance
• Meselson and Stahl
• Properties of Solids
• Scientists and the Scientific Community
• The Nature of Scientific Knowledge
• The Nitrogen Cycle
• The Phosphorus Cycle
• The Piltdown Hoax
• The Practice of Science
• The Process of Science
• Theories, Hypotheses, and Laws
• Y-Chromsome and Mitochondrial DNA Haplotypes

[noun - genetics & inheritance] An enzyme which pulls two strands of DNA apart by unwinding the DNA double helix.

• Appears in modules:

• DNA III

[noun - genetics & inheritance] An enzyme that can covalently link two double-stranded piece of DNA together by forming a phosphodiester bond between them.

• Appears in modules:

• DNA III

[noun - genetics & inheritance] An enzyme that is capable of synthesizing DNA molecules through the polymerization of nucleotides.

• Appears in modules:

• DNA III

[adjective - genetics & inheritance] Designating a genetic trait that is expressed when an organism has inherited two different variations (alleles) of a gene for that specific trait; prevailing.

• Appears in modules:

• Cellular Organelles I
• Gene Expression
• History of Earth's Atmosphere II
• Mendel and Independent Assortment
• Mendel and Inheritance
• Population Genetics
• The Nitrogen Cycle

[noun - forces, mechanics, modern physics] Describes the change in a wave's frequency experienced by an observer moving in relation to the wave's source. In the case that the wave source and observer are moving toward one another, the frequency of the observed waves increases and wavelength decreases. With sound, this would result in an increase in pitch. Conversely, for a wave source and observer moving away from one another, the wave frequency decreases and wavelength increases. With sound, this would result in a decrease in pitch. The Doppler Effect can be experienced with any wave form, including light (see redshift and blueshift).

• Appears in modules:

• The Nature of Scientific Knowledge

[person] (aka Johann Christian Doppler) Mathematician and physicist, born in Salzburg, Austria (1803-1853). Author of On the Coloured Light of the Binary Stars and Some Other Stars of the Heavens (1842), which introduced the principles behind the Doppler Effect and attempted to explain the apparent shift in wavelength of light emitted by a moving star.

• Appears in modules:

• The Nature of Scientific Knowledge

[noun - elements, materials science, matter, physical & chemical properties] The ability of a solid to be stretched to form a wire. See ductility.

• Appears in modules:

• Properties of Solids

[noun - materials science, matter, physical & chemical properties] The extent to which a solid can be stretched to form a wire. Metallic solids generally have high ductility.

• Appears in modules:

• Properties of Solids