Anything that occupies space and has mass.
A measurement of the amount of matter an object contains.
The smallest particle that can contain the chemical properties of an element.
A substance composed of atoms that cannot be broken down into smaller, simpler components.
A chart of all chemical elements currently known, organized by their properties.
A particle containing more than one atom.
A molecule containing more than one element.
The number of protons in the nucleus of a particular element.
A measurement of the total number of protons and neutrons in an element.
The spontaneous release of material from the nucleus of radioactive isotopes.
The time it takes for one-half of an original radioactive parent atom to decay.
The bond formed when elements share electrons.
A chemical bond between two oppositely charged ions.
A weak chemical bond that forms when hydrogen atoms that are covalently bonded to one atom are attracted to another atom on another molecule.
A molecule in which one side is more positive and the other side is more negative.
A property of water that results from the cohesion of water molecules at the surface of a body of water and creates a sort of skin on the water's surface.
A property of water that occurs when adhesion of water molecules to a surface is stronger than cohesion between the molecules.
A substance that contributes hydrogen ions to a solution.
A substance that contributes hydroxide ions to a solution.
The number indicating the strength of acids and bases on a scale of 0 to 14, where 7 is neutral, a value below 7 is acidic, and a value above 7 is basic (alkaline).
A reaction that occurs when atoms separate from molecules or recombine with other molecules.
law of conservation of matter
A law of nature stating that matter cannot be created or destroyed.
A compound that does not contain the element carbon or contains carbon bound to elements other than hydrogen.
A compound that contains carbon-carbon and carbon-hydrogen bonds.
A compound composed of carbon, hydrogen, and oxygen atoms.
A long chain of nitrogen-containing organic molecules known as amino acids, critical to living organisms for structural support, energy storage, internal transport, and defense against foreign substances.
Organic compounds found in all living cells, which form in long chains to make DNA and RNA.
DNA (deoxyribonucleic acid)
A nucleic acid, the genetic material that contains the code for reproducing the components of the next generation, and which organisms pass on to their offspring.
RNA (ribonucleic acid)
A nucleic acid that translates the code stored in DNA and allows for the synthesis of proteins.
Smaller organic biological molecules that do not mix with water.
A highly organized living entity that consists of the four types of macromolecules and other substances in a watery solution, surrounded by a membrane.
The ability to do work or transfer heat.
A form of energy emitted by the Sun that includes, but is not limited to, visible light, ultraviolet light, and infrared energy.
A massless packet of energy that carries electromagnetic radiation at the speed of light.
The amount of energy used when a one-watt electrical device is turned on for one second.
The rate at which work is done.
Stored energy that has not been released.
The energy of motion.
Potential energy stored in chemical bonds.
The measure of the average kinetic energy of a substance.
first law of thermodynamics
A law of nature stating that energy can neither be created nor destroyed.
second law of thermodynamics
The law stating that when energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes.
The ratio of the amount of work done to the total amount of energy introduced to the system.
The ease with which an energy source can be used for work.
Randomness in a system.
A system in which exchanges of matter or energy occur across system boundaries.
A system in which matter and energy exchanges do not occur across boundaries.
An addition to a system.
A loss from a system.
An analysis to determine inputs, outputs, and changes in a system under various conditions.
A state in which inputs equal outputs, so that the system is not changing over time.
An adjustment in input or output rates caused by changes to a system.
negative feedback loop
A feedback loop in which a system responds to a change by returning to its original state, or by decreasing the rate at which the change is occurring.
positive feedback loop
A feedback loop in which change in a system is amplified.
adaptive management plan
A plan that provides flexibility so that managers can modify it as changes occur.
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