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ChemCom Unit 1 Vocabulary
Vocabulary (as pdf)

Acid Molecular substance or other chemical that releases hydrogen ions (H+) in aqueous solution
Adsorbs Attracts and holds on its surface (charcoal, for example)
Aeration Mixing of air into a liquid; as in water flowing over a dam, or in sewage treatment
Aerobic bacteria Oxygen-consuming bacteria
Anaerobic bacteria Bacteria that do not require oxygen to live
Anion Ion possessing a negative charge
Aquifer Porous rock structures which holds water beneath the earth’s surface
Atom Smallest particles possessing the properties of an element; all matter is composed of atoms
Base Chemical that yields hydroxide ions (OH-) in aqueous solution
Biodegradable Able to be broken down into simpler substances by bacteria
Cation Ion possessing a positive charge
Chemical bond Force that holds atoms or ions together in chemical compounds
Chemical change Change in matter resulting in a change in the identity of one or more substances. Indicated by change in color, production of heat or light, creation of precipitate or gas
Chemical compound substance composed of two or more elements that cannot be separated by physical means
Chemical equation Combination of chemical formulas that represent what occurs in a chemical reaction
Chemical formula Combination of symbols that represents the elements present in a substance with subscripts showing the number of atoms of each element
Chemical property Property of a substance related to a chemical change undergone by the substance
Chemical reaction Change in matter in which one or more chemicals are transformed into new or different chemicals
Chemical symbol A one- or two- letter expression that represents an element; the symbol Na represents sodium
Chlorination Treatment of water with chlorine, for disinfection
Colloid Mixture containing large particles that are small enough to remain suspended (don’t settle)
Compound Substance composed of two or more elements that cannot be separated by physical means
Concentration Quantity of solute dissolved in a specific quantity of solvent or solution
Condensation Conversion of a substance from a gaseous to the liquid or solid state
Density Mass per volume of a given substance; = M/V
Disinfection Process to kill bacteria and disease
DO Dissolved oxygen
Electron Negatively charged particle present in all atoms
Elements Fundamental chemical substances from which all other substances are made
Evaporation Conversion of a substance form the liquid to the gas state
Filtrate liquid collected after filtration
Filtration Separation of solid particles from liquid by passing mixture through a material that retains the solid particles.
Formula unit Group of atoms or ions represented by chemical formula of a compound; simplest unit of an ionic compound
Groundwater Water which flows underground, such as well water
Hard water Water which contains calcium, magnesium or iron ions
Heavy metals Metals of high atomic mass, generally from the fifth or sixth row of the periodic table
Heterogeneous mixture A mixture which is not uniform
Homogeneous mixture A mixture which is uniform, such as a solution
Hydrologic cycle a.k.a. the Water Cycle, circulation of water between the earth’s atmosphere and Earth’s crust
Ion An atom or group of atoms that has become electrically charged by gaining or losing electrons
Ion exchange resin Material used to remove ions in water treatment
Ionic bond Attraction between oppositely charged ions in an ionic compound
Ionic compound Substance composed of ions
Molecular structure Arrangement and bonding of atoms in a molecule
Molecule Smallest particle of a substance retaining the properties of the substance; a particle composed of two or more atoms joined by chemical bonds
Neutral Neither acid or base; pH 7
Neutralization Reaction of an acid with a base, in which the characteristic properties of both are destroyed
Neutron Neutral particle present in nuclei of most atoms
Organic compounds Compound composed mainly of carbon and hydrogen atoms; a hydrocarbon
pH Number representing acidity of an aqueous solution; with pH 7 neutral, pH<7 is acidic, pH>7 is basic
Photosynthesis Process by which green plants make sugars from carbon dioxide and water in the presence of sunlight
Physical properties Distinctive characteristics such as state, density, boiling and freezing points, surface tension
Polar Having regions of positive and negative charge, as in polar molecule like water
Polyatomic ions Ion containing two or more atoms, such as PO43-
Ppm Parts per million
Precipitate Insoluble solid substance that has separated from a solution
Precipitation Rain or snow
Product Substance formed in a chemical reaction
Proton Positively charged particle present in nuclei of all atoms
Reactant Starting substance(s) in a chemical reaction
Regenerated Renewed with another chemical
Risk factor
Runoff Water which runs across the Earth’s surface before collecting in surface or groundwater
Saturated solution Solution in which the solvent has dissolved as much solute as it can hold at a given temperature
Sewage treatment plant Factory built for after-use cleaning of municipal water
SI unit Modern term for metric system
Sludge Material which settles out after wastewater treatment
Sludge gas Methane gas
Solubility Quantity of a substance that will dissolve in a given quantity of solvent to form a saturated solution
Solute The dissolved substance in a solution
Solution Homogeneous liquid mixture
Solution concentration Quantity of solute dissolved in a specific quantity of solvent or solution
Solvent The dissolving agent
States of matter 3 forms of matter; solid, liquid and gas
Subscript Character printed below a line of type; in PO43- for example, the 4 indicates the number of oxygen atoms
Supersaturated solution Solution containing a higher concentration of solute than a saturated solution at a given temperature
Superscript Character printed above a line of type; in PO43- for example, the 3- indicates the charge of the phosphate ion
Surface water Water which flow on top of the ground
Suspension Mixtures containing large easily seen particles, which settle out or form layers
Turbidity Cloudiness
Tyndall effect Pattern caused by reflection of light from suspended particles in a colloid
Universal solvent Water
Unsaturated solution Solution containing a lower concentration of solute than a saturated solution at the given temperature
Water softening Removal from water of ions that cause its hardness
Water treatment Either the pre- or post- use processing of water.