Legislating Risk

• Risk based laws – FDA

• Balancing laws– Clean Air Act– Safe Drinking Water Act

• Technology based laws– Proposition 65 in California

Controversy

• Animal experiments– Ethical?– Depend on how done?

• Cold fusion

• Greenhouse effect

• Cholesterol

Chemical Lingo

Elements

• Fundamental types of matter– Cannot be separated anymore

• All other substances are composed of 2 or more elements

• Most of the substances you know are not elements– Common elements

• Gold (24K)• Aluminum (foil)• Carbon (charcoal, diamonds, pencil “lead”)

Metals

• Shiny: Reflect light

• Opaque: Light doesn’t pass through

• Malleable: Can be hammered into shape

• Ductile: Can be drawn into wire

• Conductive: Both heat and electricity

• Most elements are metals– All are solids except mercury (Hg)

Nonmetals

• Are not malleable, ductile, or good conductors

• Solids, liquids, and gases

Symbols

• Each element has its own symbol– One or two characters– First character always capitalized– Second character never capitalized

• CO not the same as Co

• See table inside back cover

Atoms

• Smallest particle of an element with properties of the element

• Limit of chemical subdivision

• John Dalton – Theory of atoms– All matter made of atoms – 115 types →

elements– All atoms of same type are similar but

different from other types

Atoms

• John Dalton – Theory of atoms (cont.)– Relative number and arrangement of

atoms→identity– Chemical change: union, separation, or

rearrangement of atoms– Atoms are indestructible during chemical

changes• Approx. 245,000,000 atoms/inch• Have seen atoms with electron microscopes

Compound

• Chemical combination of two or more elements.– Can’t be physically separated

• Can be broken down into constituent elements using chemical means.

• Has a definite, constant, elemental composition• Has one set of properties under a given set of

conditions.• Has different properties than those of it’s

constituent elements

Mixtures

• Physical combination of two or more substances.

• Components can be separated using physical means.

• Variable compositions possible

• Variable properties as composition varies

• Heterogeneous and homogeneous

Homogeneous Mixtures

• Components are dispersed on a molecular scale

• Solutions

• Appear to be pure substances

• One set of properties for each mixture

Heterogeneous Mixtures

• Components are dispersed on a larger than molecular scale

• Do not appear to be pure substances– You can see phase boundaries

• Different properties for different parts of the mixture

Heterogeneous Mixtures

• Components are dispersed on a larger than molecular scale

• Do not appear to be pure substances– You can see phase boundaries

• Different properties for different parts of the mixture

• Sometimes may appear as a pure substance– Colloids

H2 – C1

• 2, 3, 5 - 7, 9, 10, 12, 35, 39 - 41, 43, 54