acid: a substance with an excess of available hydrogen ions; often sour in taste
acid rain: cloud or rain droplets containing pollutants (e.g., sulfuric acid, nitric acid) that make them acidic
albumin: protein found in egg whites
anthocyanin: a class of chemicals found in plants; these chemicals are often responsible for color changes
aquifer: sediment or rock in which water is stored and can flow through
atom: a very, very small particle that makes up all matter
azo dye: class of food and clothing dyes that contains a nitrogen-nitrogen double bond
bacteria: very small organisms each made of just one cell
base: a chemical or compound that takes up hydrogen ions; often bitter in taste
battery: a combination of metals and other chemicals that react together to produce electricity, i.e., moving electrons
biochemistry: the study of chemical reactions that occur within living things
biochemists: scientists who study the chemistry of life processes
biodegradable foam: a form of packaging material made of starch that has been filled with many bubbles of air; primarily used for protecting materials during shipping
biodegrade: to break down by natural processes
bromelain: enzyme from pineapples that cuts up proteins
capillary action: the tendency of small tubes to draw liquid up into them, against the force of gravity, due to the attraction of water to the molecules in the sides of the tubes
carbonate: an ion made of one carbon atom and three oxygen atoms
casein: protein found in cow milk
cell membrane: a thin barrier that surrounds the contents of plant and animal cells; provides structure and organization to the cell and controls the passage of water and other chemicals both into and out of the cell
cell wall: the rigid outermost barrier that surrounds the cell membrane; found in all plants and some algae, bacteria, and fungi; absent from all animal cells
charged atoms: atoms that have positive and negative charges
chemical bond: a connection that holds two atoms together
chemical change: when substances change their properties and their molecules change; examples include burning, rusting, forming a new material, creating gas bubbles, creating light
chemical reaction: when two or more substances combine to make a new substance; often characterized by foaming, heating, cooling, color changing
chemoreception: the way the sense of smell works the body's response to a chemical stimulus
chromatogram: a paper showing a mixture separated using chromatography
chromatography: a process scientists use to separate, analyze, or purify mixtures
concentration: the ratio of the amount of a chemical in a solution to the volume of the solution
conductor: a material that transfers heat or electricity easily
constant: a quantity, value, or condition in an experiment that is fixed, or unchanged; see also control
control: to keep a quantity, value, or condition the same in an experiment
corrode: to slowly weaken or decay, often due to chemical reactions
corrosive: causing visible destruction of human skin tissue; able to damage metals or minerals
covalent bonds: connections between atoms where the electrons are equally shared; molecules with these bonds tend to be balanced electrically
crystal: a chemical in solid form with the molecules in special arrangements; usually refers to pure solids with shiny facets and faces, such as diamonds
curcumin: the active ingredient in turmeric that changes color
curds: the solid part of milk
current: a flow of electrons
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demographer: a scientist who studies the characteristics of human populations, such as size, growth, density, distribution, and vital statistics
denature: to cause a protein to change its shape; when a protein changes its shape, it loses its properties
dense: describes how tightly packed molecules are in a substance
density: describes how tightly packed matter (molecules, people) is in a space; dense is the adjective, density is the noun; mathematically defined as a ratio of the mass of an object to the volume of the object
dependent variable: the resulting change in an experiment; the variable that is measured
diffuse: to spread out and disperse
diploid: having two copies of genetic material
dissolve: when the molecules of a substance separate and become completely surrounded by the molecules of another substance
DNA profile: a chromatogram of an individual's DNA, used to identify individuals or to diagnose disease
DNA: DeoxyriboNucleic Acid; a long molecule found in the nucleus of a cell and shaped like a double helix; carries genetic information for living things
DNase: an enzyme that breaks down DNA; "-ase" stands for enzyme
dots per inch (dpi): a measure of digital picture resolution; the number of dots that fit in a line one inch long
ductile: can be stretched or bent without breaking
electricity: created by a continuous flow of electrons through a wire
electron: negatively charged particle found in atoms
emulsifier: something added to two liquids that normally won't dissolve to keep them uniformly mixed
emulsion: a suspension of tiny droplets of one liquid in another liquid
energy: the ability to do work; anything that is not matter
enzyme: complex protein produced by cells; acts to speed up a specific biochemical reaction
evaporation: the gradual transition of a liquid or solid into a gas
exothermic: a process that releases energy, causing it to feel warm; "exo-" means "out of"
filter: a device, usually containing sand, charcoal, dirt, or some other porous material, that traps the contaminants in water when water passes through
fingerprint: unique, permanent pattern of ridges and valleys on the underside of a finger
forensic scientist: scientist who studies evidence left at a crime scene
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gas chromatography: process that uses heated gas to carry and separate a mixture into its component parts
gas: a state of matter in which molecules are spread far apart and interact only by random collisions; this state will expand to fill a container of any size
gel electrophoresis: process that uses gel and electricity to separate a mixture into its component parts; used primarily for DNA, proteins, or other biological molecules
graphite: a form of carbon used in pencils
groundwater: water that is held underground
hydrogen ion: a hydrogen atom that is missing one electron; often produced by acids and taken up by bases
hydrophilic: attracted to water; easily absorbs water and dissolves in water
hydrophobic: repelled by water; unable to absorb water or dissolve in water
hypertonic: having a higher concentration of particles in solution; "hyper-" means "more"
hypotonic: having a lower concentration of particles in solution; "hypo-" means "less"
impervious cover: material that blocks water from getting to the ground; e.g., pavement, buildings, roads, sidewalks
independent variable: the factor in an experiment that is altered by experimenter; the tested variable
indicator: a substance that changes color to indicate the presence or concentration of a certain chemical
insoluble: unable to dissolve
ionic bonds: connections between atoms where the electrons are transferred from one atom to another; molecules with these bonds tend to be highly charged
ions: an electrically charged atom or group of atoms
isotonic: having the same concentration of particles in solution; "iso-" means "same"
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lactose: sugar found in cow milk
landfill: location designated to collect trash
latent print: a fingerprint that is present, but not visible
leach: dissolving and then removing nutrients, minerals, or pollutants from the soil by running water through the soil
leaking underground storage tank (LUST): a buried container that has broken and started to leak its contents
like dissolves like: the principle in chemistry where substances with similar molecules mix well
lipids: group of organic molecules that includes oils, fats, and waxes; lipids, carbohydrates, and proteins make up the main structures of cells
liquid: a state of matter in which molecules move relatively freely and fill their container
lyse: to break open or split
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mass: the amount of matter in an object or substance; measured by weight
matter: anything that has mass and occupies space; stuff
membrane: a thin film that forms a barrier
metal: any material that is shiny, can be molded, stretched, or shaped and transfers heat or electricity; can be an element or mixture of elements
mixture: two or more substances that are mixed together but are not chemically bonded
molecule: a group of at least two atoms held together in a definite arrangement
neutral: a chemical that is neither acid nor base, and typically has a pH of 7
neutralize: to make chemically neutral (i.e., bring to a pH of 7); to make inert and less dangerous
non-point source pollution: pollution that accumulates from multiple sources
non-polar: describes neutral molecules whose charges are electrically balanced
nuclear membrane: similar to the cell membrane; surrounds the contents of the nucleus, separating it from the rest of the cell
nucleus: a compartment inside the cell that contains the cell's genetic information
octoploid: having eight copies of genetic material
osmoregulation: the process whereby living cells control the flow of water across their cell membranes
osmosis: the movement of water molecules across a barrier; water spontaneously moves from a region of low particle concentration to a region of high particle concentration
oxidation: the chemical process of losing electrons; always paired with a reduction process
oxidizer: a chemical that supplies oxygen to a reaction; a chemical that removes electrons from other atoms or molecules
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papain: enzyme from papayas that cuts up proteins
paper chromatography: process that uses paper and liquid to separate a mixture into its component parts
permeable: allows another substance to pass through
pH: a measure of the acidity or basicity of a solution, numbered on a scale where 1-6 indicates acidic, 8-14 is basic, and 7 is neutral
physical change: when substances change their properties without any changes to their molecules; e.g., melting, freezing, boiling, creating or separating a mixture, cutting, denting, scratching
plating: covering the surface of one metal with a thin layer of another metal
plume: an area where a contaminant has spread out
point-source pollution: pollution that can be traced to a specific source
polar bonds: connections between atoms where the electrons are not equally shared; molecules with these bonds tend to have a small unbalanced electrical charge
polar molecules: molecules with partial electrical charges
pollutant: an agent that can potentially harm or contaminate a resource
polymer: a large molecule made up of many repeated molecules
polystyrene: long chains of styrene molecules; this plastic is mainly used for cups and food containers
population scientist: a scientist who studies the growth and density of populations
porous: describes the amount of open spaces between particles in a material
powder: composed of particles that are too small to be seen easily
precipitate: to come out of a liquid solution as a solid; to come out of a gas solution as a liquid
pressure: continuous force applied by touching; force on a surface created by the collisions of molecules
protein: complex molecule found throughout the body; hormones, enzymes, and antibodies are all proteins, also hair, skin, nails and muscle
reaction rate: the speed at which two chemicals react with each other
recycle: use again; break down products into their component parts and remake into the same or different product
reduction: the chemical process of gaining electrons; always paired with oxidation
reducer: a chemical that supplies electrons to other atoms or molecules
retention factor: a ratio comparing how far a chemical travels compared to how far its carrier traveled; abbreviated Rf
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salting out: adding salt to a solution of water and another liquid in order to separate or purify the liquid components
silica: the main molecule in sand and quartz
solid: a state of matter in which atoms or molecules are closely and rigidly packed and resist changes in shape or volume
soluble: able to dissolve
solutes: dissolved particles in a liquid solution, e.g., salt is a solute in water when it is dissolved
starch: long chains of sugar molecules; plants create this molecule as a way to store energy
Styrofoam: brand name for polystyrene plastic that has been filled with many bubbles of air; primarily used for protecting materials during shipping
sublimation: the transition of a solid directly into a gas, without melting into a liquid first
turgid: so full of water as to be stiff and rigid
underground storage tank (UST): buried container that holds some substance; e.g., gas station tanks, septic tanks, oil tanks
urban runoff: excess water, often contaminated with pollutants, that tends to dump in streams and rivers before being filtered through the ground
variable: a changeable factor in a scientific experiment (scientists may choose to change or hold constant any particular variable)
virus: a simple, small infectious agent made from genetic material with a thin protein coat; cannot live without entering a cell so is not considered living
volume: the amount of space filled by an object or substance
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