AP Environmental Science - Chapter 2

Science

Attempts to discover order in nature and use that knowledge to make predictions about what it likely to happen in nature.

Scientific Method

The ways scientists gather data and formulate and test scientific hypotheses, models, theories, and laws.

Data

Factual information collected by scientists.

Scientific Hypothesis

A tentative explanation of a scientific law or certain scientific observations.

Model

Approximate representation or simulation of a system being studied.

Scientific Theory

A well-tested and widely accepted scientific hypothesis.

Peer Review

process of scientists reporting details of the methods and models they used, the results of their experiments, and the reasoning behind their hypotheses for other scientists working in the same field (their peers) to examine and criticize.

Scientific Law/Law of Nature

Description of what scientists find happening in nature repeatedly in the same way, without known exception.

Reliable Science

Concepts and ideas that are widely accepted by experts in a particular field of science.

Unreliable Science

Scientific results or hypotheses presented as reliable science without having undergone the rigors of the peer review process.

Tentative Science

Preliminary scientific data, hypotheses, and models that have not been widely tested and accepted.

Matter

Anything that has mass (the amount of material in an object) and takes up space. On the earth, where gravity is present, we weigh an object to determine its mass.

Element

Chemical, such as hydrogen (H), iron (Fe), etc., whose distinctly different atoms serve as the basic building blocks of all matter. Two or more elements combine to form compounds that make up most of the world’s matter.

Periodic Table of Elements

The organization of all known chemical elements according to atomic number, chemical properties, and electron configurations.

Compounds

Combination of atoms, or oppositely charged ions, of two or more elements held together by attractive forces called chemical bonds.

Atom

Minute unit made of subatomic particles that is the basic building block of all chemical elements and thus all matter; the smallest unit of an element that can exist and still have the unique characteristics of that element.

Atomic Theory

Idea that all elements are made up of atoms; the most widely accepted scientific theory in chemistry.

Neutron

Elementary particle in the nuclei of all atoms (except hydrogen-1). It has a relative mass of 1 and no electric charge.

Proton

Positively charged particle in the nuclei of all atoms. Each proton has a relative mass of 1 and a single positive charge.

Electron

Tiny particle moving around outside the nucleus of an atom. Each electron has one unit of negative charge and almost no mass.

Nucleus

Extremely tiny center of an atom, making up most of the atom’s mass. It contains one or more positively charged protons and one or more neutrons with no electrical charge (except for hydrogen-1 atom, which has one proton and no neutrons in its nucleus).

Atomic Number

Number of protons in the nucleus of an atom.

Mass Number

Sum of the number of neutrons (n) and the number of protons (p) in the nucleus of an atom. It gives the approximate mass of that atom.

Isotopes

Two or more forms of a chemical element that have the same number of protons but different mass numbers because they have different numbers of neutrons in their nuclei.

Molecule

Combination of two or more atoms of the same chemical element or different chemical elements held together by chemical bonds.

Ion

Atom or group of atoms with one or more positive (+) or negative (−) electrical charges.

Acidity

Comparative amounts of hydrogen ions and hydroxide ions contained in a particular volume of a solution when a substance is dissolved in water. An acid solution has more hydrogen ions than hydroxide ions and a basic solution has more hydroxide ions than hydrogen ions.

pH

Numeric value that indicates the relative acidity or alkalinity of a substance on a scale of 0 to 14, with the neutral point at 7. Acidic solutions have a pH less than 7 and basic solutions have a pH greater than 7.

Chemical Formula

Shorthand way to show the number of atoms (or ions) in the basic structural unit of a compound.

Organic Compounds

Compounds containing carbon atoms combined with each other and with atoms of one or more other elements such as hydrogen, oxygen, nitrogen, sulfur, phosphorus, chlorine, and fluorine. All other compounds are called inorganic compounds.

Complex Carbohydrates

Molecules consisting of carbon, hydrogen, and oxygen that provide energy to living organisms. Sugar, starch, and cellulose are examples.

Proteins

Structural molecules consisting of a specific sequence of amino acids that serve as components of body tissue and as enzymes.

Nucleic Acids

Informational molecules such as DNA or RNA in a double-helix shape consisting of complementary nucleotides in a specific sequence.

Lipids

Energy storing organic molecule such as fats, oils, and waxes.

Cells

Smallest living unit of an organism.

Cell Theory

The idea that all living things are comprised of cells.

Genes

Coded units of information about specific traits that are passed from parents to offspring during reproduction. They consist of segments of DNA molecules found in chromosomes.

Trait

Characteristic passed on from parents to offspring during preproduction in an animal or plant.

Physical Change

Process that alters one or more physical properties of an element or a compound without changing its chemical composition.

Chemical Change

Interaction between chemicals in which the chemical composition of the elements or compounds involved changes.

Chemical Reaction

Interaction of chemicals in which the composition of the elements or compounds involved changes.

Law of Conservation of Matter

In any physical or chemical change, no atoms are created or destroyed.

Energy

Capacity to do work by performing mechanical, physical, chemical, or electrical tasks or to cause heat transfer between two objects at different temperatures.

Kinetic Energy

Energy that matter has because of its mass and speed, or velocity.

Electric Power

Rate at which electric energy is transferred by an electric circuit.

Electromagnetic Radiation

Form of kinetic energy traveling as electromagnetic waves.

Heat Energy/Thermal Energy

Total kinetic energy of all randomly moving atoms, ions, or molecules within a given substance, excluding the overall motion of the whole object.

Radiation

Fast-moving particles or waves of energy.

Conduction

The process by which heat or electricity is directly transmitted through a substance when there is a difference of temperature or of electrical potential between adjoining regions.

Convection

The transfer of heat via the movement in a gas or liquid in which the warmer parts move up and the colder parts move down.

Potential Energy

Energy stored in an object because of its position or the position of its parts.

Nuclear Energy

Energy released when atomic nuclei undergo a nuclear reaction such as the spontaneous emission of radioactivity, nuclear fission, or nuclear fusion.

Renewable Energy

Energy that comes from resources that are replaced by natural processes continually or in a relatively short time.

Nonrenewable Energy

Resource that exists in a fixed amount in the earth’s crust and has the potential for renewal by geological, physical, and chemical processes taking place over hundreds of millions to billions of years.

Energy Quality

Ability of a form of energy to do useful work.

High-Quality Energy

Energy that is concentrated and has great ability to perform useful work.

Low-Quality Energy

Energy that is dispersed and has little ability to do useful work.

First Law of Thermodynamics/Law of Conservation of Energy

Whenever energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed, but energy can be converted from one form to another.

Second Law of Thermodynamics

Whenever energy is converted from one form to another in a physical or chemical change, we end up with lower-quality or less usable energy to do useful work. Some of the initial energy input is always degraded to lower-quality, more dispersed, less useful, usually low-temperature heat that flows into the environment.

Energy Efficiency

Percentage of the total energy input that does useful work and is not converted into low-quality, generally useless heat in an energy conversion system or process.

System

Set of components that function and interact in some regular and theoretically predictable manner.

Inputs

Matter, energy, or information entering a system.

Flows/Throughputs

Rate of flow of matter, energy, or information through a system.

Outputs

Matter, energy, or information leaving a system.

Feedback

Any process that increases (positive feedback) or decreases (negative feedback) a change to a system.

Feedback Loop

Occurs when an output of matter, energy, or information is fed back into the system as an input and leads to changes in that system.

Positive Feedback Loop

Feedback loop that causes a system to change further in the same direction.

Ecological Tipping Point

Point at which an environmental problem reaches a threshold level, which causes an often irreversible shift in the behavior of a natural system.

Negative Feedback Loop/Collective Feedback Loop

Feedback loop that causes a system to change in the opposite direction.