A set of mystical beliefs based on the idea that ordinary matter can be perfected. Though it was a pseudo-science, alchemy, which flourished in the late Middle Ages, was a forerunner of scientific chemistry.
In general, an atmosphere is a blanket of gases surrounding a planet. Unless otherwise identified, however, the term refers to the atmosphere of Earth, which consists of nitrogen (78%), oxygen (21%), argon (0.93%), and other substances that include water vapor, carbon dioxide, ozone, and noble gases such as neon (0.07%).
The number of protons in the nucleus of an atom. Since this number is different for each element, elements are listed on the periodic table in order of atomic number.
The changes that particular elements undergo as they pass back and forth through the various earth systems and particularly between living and nonliving matter. The elements involved in biogeochemical cycles are hydrogen, oxygen, carbon, nitrogen, phosphorus, and sulfur.
A combination of all living things on Earth—plants, mammals, birds, amphibians, reptiles, aquatic life, insects, viruses, single-cell organisms, and so on—as well as all formerly living things that have not yet decomposed.
A meat-eating organism.
The joining through electromagnetic force of atoms that sometimes, but not always, represent more than one chemical element. The result is the formation of a molecule.
A one-letter or two-letter abbreviation for the name of an element.
A substance made up of atoms of more than one element chemically bonded to one another.
Organisms that obtain their energy from the chemical breakdown of dead organisms as well as from animal and plant waste products. The principal forms of decomposers are bacteria and fungi.
A chemical reaction in which a compound is broken down into simpler compounds or into its constituent elements. In the earthsystem, this often is achieved through the help of detritivores and decomposers.
Organisms that feed on waste matter, breaking organic material down into inorganic substances that then can become available to the biosphere in the form of nutrients for plants. Their function is similar to that of decomposers;however, unlike decomposers—which tend to be bacteria or fungi—detritivores are relatively complex organisms, such as earthworms or maggots.
A term referring to a community of interdependent organisms along with the inorganic components of their environment.
A substance made up of only one kind of atom. Unlike compounds, elements cannot be broken chemically into other substances.
A state of heightened biological productivity in a body of water, which is typically detrimental to the ecosystem in which it takes place. Eutrophication can be caused by an excess of nitrogen or phosphorus in the form of nitrates and phosphates, respectively.
A term describing the interaction of plants, herbivores, carnivores, omnivores, decomposers, and detritivores, each of which consumes nutrientsand passes it along to other organisms.
A branch of the earth sciences, combining aspects of geology and chemistry, that is concerned with the chemical properties and processes of Earth—inparticular, the abundance and interaction of chemical elements and their isotopes.
The upper part of Earth's continental crust, or that portion of the solid earth on which human beings live and which provides them with most of their food and natural resources.
A plant-eating organism.
The entirety of Earth's water, excluding water vapor in the atmosphere but including all oceans, lakes, streams, groundwater, snow, and ice.
The removal of soil materials that are in solution, or dissolved in water.
A naturally occurring, typically inorganic substance with a specific chemical composition and a crystalline structure.
A substance with a variable composition, meaning that it is composed of molecules or atoms of differing types. Compare with compound.
A group of atoms, usually but not always representing more than one element, joined in a structure. Compounds typically are made up of molecules.
An organism that eats both plants and other animals.
At one time chemists used the term organic only in reference to living things. Now the word is applied to most compounds containing carbon, with the exception of carbonates (which are minerals) and oxides, such as carbondioxide.
A chart that shows the elements arranged in order of atomic number along with their chemical symbols and the average atomic mass for each particular element.
The biological conversion of light energy (that is, electromagnetic energy) from the Sun to chemical energy in plants.
A term referring to the ability of one element to bond with others. The higher the reactivity, the greater the tendency to bond.
Material deposited at or near Earth's surface from a number of sources, most notably preexisting rock. There are three types of sediment: rocks, or clastic sediment; mineral deposits, or chemical sediment; and organic sediment, composed primarily of organic material.
Capable of being dissolved.
A homogeneous mixture(i.e., one that is the same throughout) in which one or more substances is dissolved in another substance—for example, sugar dissolved in water.
The breakdown of rocks and minerals at or near the surface of Earth due to physical, chemical, or biological processes.
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