APES Chapter 2

acidity

a chemical characteristic that helps determine how a substance dissolved in water will interact with and affect its environment

atom

The most basic building block of matter is an atom: the smallest unit of matter into which an element can be divided and still retain its chemical properties.

atomic number

equal to the number of protons in the nucleus of its atom

atomic theory

the most widely accepted scientific theory in chemistry that states the idea that all elements are made up of atoms

cells

the fundamental structural units of life

chain reaction

Multiple fissions within a certain amount of mass produce a chain reaction, which releases an enormous amount of energy.

chemical change, or chemical reaction

In a chemical change, or chemical reaction, there is a change in the arrangement of atoms or ions within molecules of the substances involved.

chemical formula

Chemists use a chemical formula to show the number of each type of atom or ion in a compound.

chromosome

Thousands of genes, in turn, make up a single chromosome, a special DNA molecule together with a number of proteins.

compounds

combinations of two or more different elements held together in fixed proportions.

data

information needed to answer their questions�scientists make observations of the subject area they are studying.

deductive reasoning

involves using logic to arrive at a specific conclusion based on a generalization or premise.

electromagnetic radiation

another form of kinetic energy, energy travels in the form of a wave as a result of changes in electric and magnetic fields.

electrons (e)

negatively charged subatomic particles

elements

each of which is a fundamental substance that has a unique set of properties and cannot be broken down into simpler substances by chemical means.

energy

the capacity to do work or transfer heat. Work is done when something is moved.

Energy efficiency, or energy productivity

a measure of how much useful work is accomplished by a particular input of energy into a system.

energy quality

a measure of an energy source's capacity to do useful work

experiments

procedures carried out under controlled conditions to gather information and test ideas

feedback

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

feedback loop

a process that 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

genes

certain sequences of nucleotides within some DNA molecules

heat

Another form of kinetic energy is heat: the total kinetic energy of all moving atoms, ions, or molecules within a given substance.

high-quality energy

is concentrated and has a high capacity to do useful work.

high-quality matter

is highly concentrated, is typically found near the earth's surface, and has great potential for use as a resource.

inductive reasoning

involves using specific observations and measurements to arrive at a general conclusion or hypothesis.

inorganic compounds

Table sugar, vitamins, plastics, aspirin, penicillin, and most of the chemicals in your body are organic compounds, which contain at least two carbon atoms combined with atoms of one or more other elements. All other compounds are called inorganic compoun

inputs/flows or throughputs/outputs

Most systems have the following key components: inputs from the environment, flows or throughputs of matter and energy within the system at certain rates, and outputs to the environment.

ion

an atom or groups of atoms with one or more net positive or negative electrical charges (building block of matter)

isotopes

Forms of an element having the same atomic number but different mass numbers

kinetic energy

Moving matter has kinetic energy because it has mass and velocity.

law of conservation of energy

(first law of thermodynamics) When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed.

law of conservation of matter

when a physical or chemical change occurs, no atoms are created or destroyed.

low-quality energy

is dispersed and has little capacity to do useful work

mass number

the total number of neutrons and protons in its nucleus

matter

anything that has mass and takes up space

matter quality

a measure of how useful a form of matter is to humans as a resource, based on its availability and concentration, or amount of it that is contained in a given area or volume.

model

an approximate representation or simulation of a system being studied.

molecule

a combination of two or more atoms of the same or different elements held together by forces called chemical bonds (building block of matter)

natural radioactive decay

isotopes spontaneously emit fast-moving subatomic particles, high-energy radiation such as gamma rays, or both

negative, or corrective, feedback loop

causes a system to change in the opposite direction from which it is moving

neutrons (n)

a subatomic particle with no electrical charge

nuclear changes

changes in the nuclei of its atoms (3 types)

nuclear fission

a nuclear change in which the nuclei of certain isotopes with large mass numbers (such as uranium-235) are split apart into lighter nuclei when struck by neutrons; each fission releases two or three neutrons plus energy.

nuclear fusion

a nuclear change in which two isotopes of light elements, such as hydrogen, are forced together at extremely high temperatures until they fuse to form a heavier nucleus.

nucleus

an extremely small and dense center of an atom �which contains one or more protons and, in most cases, one or more neutrons.

organic compounds

contain at least two carbon atoms combined with atoms of one or more other elements (table sugar, vitamins, plastics, aspirin, penicillin, and most of the chemicals in your body)

paradigm shift

when new discoveries and new ideas overthrow a well-accepted scientific theory or law

peer review

happens when scientists report 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

pH

a measure of acidity, based on the amount of hydrogen ions (H+) and hydroxide ions (OH-) contained in a particular volume of a solution

physical change

when a sample of matter undergoes change but its chemical composition, or the arrangement of its atoms or ions within molecules, does not change

positive feedback loop

causes a system to change further in the same direction

potential energy

stored energy that is potentially available for use

protons (p)

positively charged subatomic particles

radioactive decay

occurs when nuclei of unstable isotopes spontaneously emit fast-moving chunks of matter (alpha particles or beta particles), high-energy radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of

radioactive isotopes or radioisotopes

unstable isotopes

reliable science

consists of data, hypotheses, theories, and laws that are widely accepted by scientists who are considered experts in the field under study.

science

an endeavor to discover how nature works and to use that knowledge to make predictions about what is likely to happen in nature.

scientific hypothesis

a possible and testable explanation of what they observe in nature or in the results of their experiments.

scientific law, or law of nature

a well-tested and widely accepted description of what we find happening over and over again in the same way in nature

scientific theory

A well-tested and widely accepted scientific hypothesis or a group of related hypotheses

second law of thermodynamics

When energy changes from one form to another, we always end up with lower-quality or less usable energy than we started with. This lower-quality energy usually takes the form of heat given off at a low temperature to the environment.

synergistic interaction, or synergy

occurs when two or more processes interact so that the combined effect is greater than the sum of their separate effects.

system

a set of components that function and interact in some regular way.

tentative science or frontier science

Sometimes, preliminary results that capture news headlines are controversial because they have not been widely tested and accepted by peer review. They are not yet considered reliable, and can be thought of as tentative science or frontier science.

time delays

Complex systems often show time delays between the input of a feedback stimulus and the response to it.

tipping point

Time delays can allow an environmental problem to build slowly until it reaches a threshold level, or tipping point, causing a fundamental shift in the behavior of a system

trait

Each of these coded units of genetic information concerns a specific trait, or characteristic passed on from parents to offspring during reproduction in an animal or plant.

unreliable science

Scientific hypotheses and results that are presented as reliable without having undergone the rigors of peer review, or that have been discarded as a result of peer review, are considered to be unreliable science