Chemistry 1100 reading notes1.2•Adults breathe about 11,000 liters (3,000 gallons) of air per day•Air is a mixture: a physical combination of two or more pure substances present in variable amounts•Major components of air: nitrogen (78%), oxygen (21%), argon, carbon dioxide and water vapor•Oxygen is absorbed into our blood via the lungs and reacts with the foods we eat to release the energy to power the chemical processes within our bodies. •Oxygen isolated as pure substance in 1774•During respiration the foods we eat are metabolized to produce carbon dioxide and water•Parts per million (ppm): one ppm is a unit of concentration 10,000 times smaller than 1% (one part per hundred)•No such thing as pure air•Four gases contribute to air pollution at the surface of the Earth: carbon monox-ide, ozone, sulfur dioxide, and nitrogen dioxide•Carbon monoxide (CO) has earned the nickname “silent killer”––interferes with the ability of your hemoglobin to carry oxygen•Ozone (O3) has a sharp odor and can reduce the lung function in healthy people•Sulfur Dioxide (SO2) has a sharp & unpleasant odor, it dissolves in the moist tis-sue of your lungs to form and acid.•Nitrogen dioxide (NO2) is a brown color and also damages lung tissue•Particulate matter (PM) is classified by size. PM10 includes particles with an av-erage diameter of 10 um of less, a length on order of 0.0004 inches. •Tinier and more deadly particles are sometimes called fine particles1.3•Risk assessment is the process of evaluating scientific data and making predic-tions in an organized manner about the probabilities of an outcome•In the U.S., national air quality standards were established in 1970 as a result of the Clean Air ActChemistry 1100 reading notes•Toxicity: the intrinsic health hazard of a substance •Exposure: the amount of the substance encountered •Exposure is far more straightforward to asses than toxicity because exposure de-pends on factors that we more easily can measure•Ambient Air: refers to the air surrounding us, usually meaning the outside air•Measurements of exposure include:•Concentration in the air: the more toxic the pollutant, the lower the concentration must be set. Microgram (ug): is a millionth of a gram or 10^-6 g•Length of time: the higher concentrations of a pollutant can be tolerated only briefly•Rate of Breathing: if air quality is poor, reducing activity is one way to reduce expo-sure•Scientific Notation: a system for writing numbers as the product of a number and 10 raised to the appropriate power.•Parts per billion (ppb): one part out of one billion, or 1000 times less concen-trated than one part per million•Air Quality Index (AQI) – green/yellow = good, orange = okay, red/purple = bad1.5•About 75% of the air is found within about 6 miles of the surface of our planet•Troposphere is the lower region of the atmosphere in which we live that lies di-rectly above the surface of the Earth•The warmest air in the troposhere usually lies at ground level because the Sun heats the ground, which in turn warms the air above it. Cooler air is found higher up.•Air pollutants can accumulate in an inversion layer, especially if the layer remains stationary for an extended period.•Sustainability: meeting the needs of the present without compromising the abil-ity of future generations to meet their needs•Green Chemistry: “benign by design.” It calls for designing chemical products and processes that reduce of eliminate the use or generation of hazardous sub-stances. Green chemistry reduces pollution through the design or redesign of chemi-Chemistry 1100 reading notescal processes. The goal is to use less energy, create less waste, use fewer resources and use renewable resources.•Shifting baseline: the idea that what people expect as “normal” on our planet has changed over time especially with regard to ecosystems. •Element: one of the 100 or so pure substances in our world from which com-pounds are formed•About 90 elements occur naturally on Earth•Majority of elements are solids•Atom: the smallest unit of an element that can exist as a stable, independent en-tity •Molecule: two or more atoms held together by chemical bonds in a certain spa-tial arrangement•Compound: a pure substance made up of two or more different elements in a fixed, characteristic chemical combination. Compounds contain two or more different types of atoms.•Chemical symbols are one-or two-letter abbreviations for the elements •A new element #117 was reported in 2010 and currently is the heaviest element known•Dmitri Mendeleev developed the periodic table•Periodic Table: an orderly arrangement of all the elements based on similarities in their properties. •Metals–– elements that are shiny and conduct electricity and heat well•Nonmetals–– elements that do not conduct heat or electricity well and have no onecharacteristic appearance •Metalloids–– elements that lie between metals and nonmetals on the periodic tableand do not fall cleanly into either category •groups: vertical columns that organize elements according to important propertiesthat they have in common and are numbered from left to right•Halogen: one of the reactive nonmetals in Group 7A•Noble Gas: one of the inert elements in Group 8A that undergoes few, if any, chemical reactionsChemistry 1100 reading notes•Elements have the ability to combine in many different ways•Every compound exhibits a constant characteristic chemical composition