Chapter 8 Chemistry and the Environment

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Chapter 8Chemistry and the Environment

• Objectives
• Explain the kinds, states, and properties of
  matter
• Explain how matter is classified
• Describe types of chemical elements and how they
  are organized in a periodic table
• Describe chemical reactions, compounds, and
  bonding
• Explain pH and how it can be modified
• Identify major chemical environmental hazards

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Terms
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The Nature of What We Have

• The world around us is made of chemicals
• A chemical is a substance produced by or used in
  a chemical process
• Plants carry out chemical processes by
  photosynthesis
• Animals carry out chemical processes by digestion
• Chemicals are much more helpful to us than they
  are harmful to us

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Matter

• Matter is anything that has mass and volume
• Mass is the quantity of matter in an object
• Mass and Weight
• Volume means that something occupies space or has
  bulk

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Energy

• Energy is the ability to do work or cause change
• Matter contains stored chemical energy
• Some matter can produce thermal energy, radiant
  energy, or electrical energy
• The energy of an object in motion is called
  kinetic energy

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Matter is in different states
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Why States of Matter Change

• Temperature
• Pressure

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Matter has two types of properties physical and
chemical

• Physical properties
• Physical properties are mass, color, shape,
  boiling, length, volume, and others

• Chemical properties
• Such properties are observed when substances are
  converted to new substances with different forms

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Classification of Matter

• Pure substance
• A pure substance has uniform and consistent
  composition and properties from one sample to an
  other
• Pure substances of the same kind differ from
  other kind and are identified by their properties
• Salt, sugar, gold, oxygen, aluminum

• Mixtures
• A mixture is a combination of two or more
  different kinds of matter and is not definite in
  the proportions of its content
• Substance in a mixture can be separated based on
  unique properties
• For example, if water containing sugar is
  evaporated, the sugar remains behind

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Solutions

• Homogeneous mixture
• A solution may be of solids, liquids, or gases
• Air is a uniform mixture of nitrogen, oxygen, and
  other gases
• Drinking water may contain minerals, gases, and
  other substances

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Suspensions

• A suspension is the distribution of small
  particles in a fluid dispersion medium
• Two kinds of suspensions are commonly found
  emulsion and colloidal suspensions

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Suspensions

• Emulsions
• An emulsion is a suspension of two solutions,
  such as tiny oil droplet in water
• Emulsion tend to separate

• Colloidal suspension
• Colloidal suspensions are solid materials in a
  fluid, such as soil particles in water or dust in
  the air
• Solid materials can be removed from colloidal
  suspensions with filters

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Elements from Compounds

• Pure substances are either elements or compounds
• Water, a pure substance, is made of hydrogen and
  oxygen
• Hydrogen and oxygen are elements that are also
  pure substances

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Element do not decompose

• An element is a pure substance that cannot be
  broken down into other substances by ordinary
  chemical change

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Compounds Decompose

• A compound is a pure substance that can decompose
  into simpler substances

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Chemical Elements The Ingredients of Matter

• Chemical elements are substances consisting
  entirely of atoms of the same atomic number
• Everything on earth is made of chemical elements
• 111 chemical elements have been identified
• 19 are artificial (created in a laboratory)
• 92 are natural elements (found on the earth)

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Names and Symbols
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Types of Elements

• Metals

• Nonmetals
• Metalloids
• Noble gases

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Metals

• A metal has a metallic luster, is malleable (can
  be shaped by hammering) and ductile, and has a
  high tensile strength
• Metals are good conductors of heat and
  electricity
• All elements except mercury are solids at room
  temperature
• Eighty-five elements are classified as metals

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Nonmetals

• A nonmetal is a poor conductor of heat and
  electricity
• Some nonmetals are gases under ordinary
  conditions, such as oxygen, nitrogen etc.
• Eleven elements are classified as nonmetals

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Metalloids

• The metalloids are between the metals and
  nonmetals in the periodic table
• They are somewhat like metals and may have a
  metallic luster
• Two examples are arsenic and antimony
• Metalloids also are semiconductor of electricity
• Only six elements are classified as metalloids

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Noble Gases

• Six elements are classified as noble gases
• The elements do not readily react with other
  elements under ordinary conditions
• Several noble gases such as neon, argon, and
  helium are common elements

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Atoms

• An atom is the smallest part of an element that
  can take part in a chemical reaction
• Atoms of different have differing properties

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Atomic Structure

• All atoms have two regions the nucleus and
  electron regions
• The nucleus contains protons and neutrons

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Atomic Numbers

• The atomic number is the number of protons in the
  nucleus

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Atomic Mass

• The atomic mass of an element is the total number
  of protons and neutrons in the nucleus of an atom
• Atomic mass is called the atomic weight of the
  element
• The average atomic mass of elements is important
  because they indicate relationships in chemical
  reactions

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Reactions

• A chemical reaction occurs when two or more
  substances, known as reactants, interact
  resulting in chemical changes in the substances
  so a new substance forms
• The new substance has different properties from
  the original substances

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Types of Reactions

• Composition reaction takes place when two or more
  substances react to form a more complex product
• 2Na Cl2 2NaCl
• Decomposition is the breaking down of chemical
  compounds, it occurs when one substance breaks up
  to form or more products
• 2NaCl 2Na Cl2
• Single replacement occurs when one element
  replaces another element in a compound
• Zn 2HCl ZnCl2 H2
• Double replacement is an ionic reaction when two
  compounds exchange elements
• NaOH HCl NaCl H2O
• Redox is a sum of oxidation and reduction changes
• Oxidation occurs when an atom loses electrons
• Reduction is when an atom gains electrons

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Evidence of Chemical Reactions

• Heat
• Light
• Gas
• Color
• Precipitate
• Violent

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Compound

• Chemical bonding
• Ionic bond
• Covalent bond
• Molecules
• Electron valence
• Organic and inorganic compounds

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Organic and Inorganic Compounds

• Organic compounds
• All organic compounds contain carbon
• OCs normally do not dissolve in water but will
  dissolve in organic liquid, such as alcohol and
  chloroform
• OCs are more easily decomposed by heat, when
  heated or burned, OCs leave a black residue of
  carbon

• Inorganic compounds
• Most inorganic compounds do not contain carbon
• ICs usually dissolve in water
• ICs are difficult to burn
• Just compare what happen when sugar (an organic
  compound) and salt (an inorganic compound) are
  heated

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Names, Formulas, and States
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pH

• pH represents the number of hydrogen ions in a
  solution
• Pure water will not conduct electricity, it is
  neutral and has a pH of 7.0
• pH is measured with a pH meter or litmus paper

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Acids and Acidity

• Most acid solutions contain hydrogen
• Sulfuric acid, acetic acid, citric acid
• Acids have a characteristically sour taste

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Bases and Basicity

• A base is a compound that produces hydroxide ions
  and reacts with acids to form salts
• Alkaline compound
• Sodium bicarbonate, calcium carbonate

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Salts

• Combining acids and bases produces a salt
• Salts have a pH nearer 7.0
• Example, NaCl
• Water and soil can react to create salt, an
  example is using irrigation water containing a
  base on land with acidic soil pH

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Chemical Sources of Environmental Hazards
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Heavy Metals

• Heavy metals are elements with high atomic
  weights or masses

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Organic Compounds

• Organic compound naturally occur or may be
  manufactured
• Those manufactured are known synthetic organic
  compounds (SOCs)
• All SOCs contain carbon
• SOCs are not decayed by microorganism and may get
  into the food chain
• Such as, detergent, pesticides, petroleum,
  hydrocarbon, chlorofluorocarbon

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Nonmetal Oxides

• Nonmetal oxides typically cause air pollution
  problems
• The major elements involved are sulfur, carbon,
  and nitrogen
• Acid rain (SO2, SO3 H2O H2SO4)
• Destruction of the ozone layer
• The greenhouse effect
• Carbon monoxide (CO)
• Nitrogen oxides (NO and NO6)

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Radioactivity

• Radioactivity is caused by the instability of the
  atomic nucleus in certain atoms
• Ionizing radiation
• Nonionizing radiation
• Such as, radon is produced by the decay of radium
  found in the soil

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Hazardous Materials Classification

• Explosive
• Gases
• Flammable liquids
• Flammable solids
• Oxidizing agents
• Toxic materials
• Radioactive materials
• Corrosives
• Miscellaneous

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Methods of Land Disposal

• Deep-well injection
• Surface impoundment
• Landfills

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Future Management of Hazardous Wastes

• Incineration
• Biodegradation
• Pollution avoidance

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Tests

• What is matter?
• Distinguish between a pure substance and a
  mixture
• What is the periodic table? How is it useful?
• What are the kinds of reactions?
• What evidence shows that one has occurred?
• What is pH and how does it vary?
• What are the major areas of chemical
  environmental hazards?