Science & Technology in the Environment Chemistry

15.01 – Define terms and the state, properties, and classification of matter related to density and the environment.

General Terms  Chemical  Chemistry  Matter  Mass  Volume  Energy

Chemistry Terms  Chemical  A substance produced by or used in a chemical process  Chemistry  The study of the composition of matter and the energy created by the interaction of matter  Matter  Anything that has mass and volume

Chemistry Terms  Mass  The quantity of matter in an object  A measure of an object’s resistance to moving or being moved  Often determined by weighing with a scale  Weight and mass can be different in differing places  “altitude”  Volume  Means that something occupies space  Energy  The ability to do work or cause change

Energy  Potential  Energy of matter because of its position or compositions  It is stored in the matter  Kinetic  The energy of an object in motion

States of Matter  Solid  Definite shape and volume  Examples: wood, stone, glass, etc.  Liquid  Has a definite volume and takes the shape of its container  Examples: water, oil, etc.  Gaseous  Has neither a definite shape or volume  Can expand and contract and move around  Example: air.  It can be made to fit in various shapes, like a tire, and can be compressed.

Why States of Matter Change  Matter may change from one state to another  Usually related to temperature and pressure  When water is cooled, it turns to ice, a solid  When water is boiled, it turns to steam, a gas  The properties do not change

Properties of Matter  Property  A characteristic or feature that makes it possible to distinguish between kinds of matter  Two Properties  Physical  Can be observed or measured without altering the matter  Mass, Color, Shape, Length  Chemical  Describes the changes matter goes through when its identity is altered or changed to create substances in different forms  Describes the change it undergoes in altering its identity.  Burning wood. Wood becomes ash and carbon dioxide, as well as heat and light.

Classification of Matter  Pure substances  Matter that has uniform and consistent composition and properties from one sample to another.  Salt and Sugar  Mixtures  A combination of two or more different kinds of matter, and it is not definite in the proportions of its contents.  Types  Solution – Homogenous mixture. Can be solid, liquid, or gas  Suspension – when particles are dispersed in a fluid medium.  Water in a stream.

Chemistry – Discuss chemical elements, compounds, reactions, formulas, and equations.

Compounds  Elements form compounds  Pure substances are either elements or compounds  Elements do not decompose  An element is a pure substance that cannot be broken down into other substances.  Examples: gold, silver, and iron

Elements  A substance consisting entirely of atoms of the same atomic number  Everything on Earth is made of chemical elements  114 chemical elements have been identified  92 are natural elements found on Earth  The rest are made in a laboratory

Names and Symbols  All have a name and symbol  Symbols are either one or two letters  Some officially unnamed have three letters  Letters used are often letters from the English spelling of the word  AL for Aluminum  N for Nitrogen  O for Oxygen  C for Carbon  Some are from Latin  Ag for Silver, old name was argentum  K for Potassium  Fe for Iron

Organizing the Elements  Grouped in the Periodic Table  An arrangement of chemical elements in the order of increasing atomic number. It is in rows and columns.

Types of Elements  Metals  An element with metallic luster  Can be shaped  Are electrical conductors  Iron, Aluminum, and Copper  Nonmetals  Poor conductor of heat and electricity  Oxygen, Nitrogen, Carbon, and Sulfur  Eleven elements classified as nonmetallic

Types of Elements (continued)  Metalloids  Between metals and nonmetals both in the periodic table and in properties  Arsenic  Six elements classified as metalloids  Noble Gases  Do not normally react with other elements  Neon and Helium  Six elements are classified as noble gases.

Atoms, Atomic Number, and Masses  Atom  Small part of an element that can take part in a reaction  Atomic Structure  The arrangement of the parts of atoms  Atomic Number  The number of protons in the nucleus  Atomic Mass  The total number of protons and neutrons in the nucleus.

Chemical Reactions and Compounds  What occurs when a substance becomes another substance with different characteristics  Types  Composition – 2 or more substances react to form a more complex product  Decomposition – when chemical compounds break down  Single Replacement – when one element replaces another in a compound  Double Replacement – When two compounds exchange elements

Compounds  Forms when two or more elements unite to form a substance with qualities different from the elements alone  Chemical Bonding  New compounds are formed when elements bond  Chemical bonding is two or more elements joining together to form a compound.  Molecules  Smallest amount of a substance that can exist independently and keep the properties of the substance  Water – two hydrogen atoms and one oxygen atom  Calcium Carbonate (limestone) C 2 CO 3  Carbon dioxide CO 2  Glucose C 6 H 12 O 6

Formulas and Equations  The combination of chemical symbols and numbers that depict a compound  Shows the element symbols and formulas, the reactants, and the products of a chemical reaction.  Example:  Photosynthesis Equation  12H 2 O + 6CO 2 + sunlight and chlorophyll = C 6 H 12 O 6 + 6O H 2 O

Chemistry – Demonstrate the ability to determine the pH and salts of material and relate it to environmental conditions.

pH  Strength of hydrogen ion concentration, measured as potential hydrogen or pH  14 point scale is used  Water is neutral = 7  Solutions below 7 (0 to 6.9) are acid  Solutions above 7.0 (7.1 to 14) are basic or alkaline  The greater the distance from 7, or neutral, the stronger the substance.  9 is more basic or alkaline than 7.1  5 is more acidic than 6.9

pH  Plants need the correct pH to grow properly  Different plants require different pH  Range is for most plants  Important for animals, especially fish  Relates to decomposition  Microorganisms cannot survive well in an improper pH and decay will be stopped  Acids are used to preserve food, like pickles in vinegar (acetic acid)

pH  Measurements are normally performed with:  pH or litmus paper  pH meter  Most acids contain hydrogen  Sulfuric acid is H 2 SO 4  Acetic acid (vinegar) is CH 3 CO 2 H  Bases produce hydroxide ions  React with acids to produce salts  Baking soda (sodium bicarbonate) NaHCO 3 and limestone (calcium carbonate) CaCO 3 are examples.

Salts  Formed when acids and bases are combined  NaCl = table salt  Concentrations can build up in water and soil  Often by soil and water reacting  Example  Irrigation water containing a base is used on an acidic soil; can be on fields or in a container  Can result in unproductive land  Can also result from using certain fertilizers

Chemistry – Discuss chemical sources of environmental hazards.

Chemical Sources of Environmental Hazards  Heavy Metals  An element with a high atomic weight or mass  Lead, mercury, and cadmium  Are poisonous in small amounts  Organic Compounds  Detergents – contained phosphates that caused phosphate build-up and damaged ponds  Pesticides – materials used to control pests  Petroleum – fossil fuel used in making gasoline, diesel fuel, lubricants, and other products.  Chloroflurocarbons (CFCs) – used in aerosols and refrigerants (AC and Fridge); may have contributed to the damage of the ozone layer

Chemical Sources of Environmental Hazards  Nonmetal Oxides  Elements whose oxides form acids  Sulfur forming into sulfur oxide and then reacting with water to form sulfuric acid  S + O  SO 2 or SO 3 + H 2 O  H 2 SO 4  May cause air pollution  Radioactivity  Caused by the instability of the atomic nucleus of certain atoms  Radium decaying into radon, which can enter buildings and cause injury to people

Health Affects of Pollution

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