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2013-01-19 23:33:01

study items ch. 2
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  1. What is matter?
    anything that has mass and occupies space
  2. States of matter
    Solid - definite shape and volume (i.e. bone)

    Liquid - definite volume, changeable shape (blood)

    Gas - changeable shape and volume (air)
  3. What is energy?
    Energy is the capacity to do work or put matter into motion.

    Has no mass
  4. Types of energy
    Kinetic - energy in action

    Potential - stored/inactive energy
  5. Forms of energy
    • Chemical energy - stored in bonds of chemical substances
    • Electrical energy - results from movement of charged particles
    • Mechanical energy - directly involved in moving matter
    • Radiant or electromagnetic energy - exhibits wavelike properties (visible light, ultraviolet light, x-rays)
  6. How can energy forms be converted?
    energy may be converted from one form to another (i.e. from kinetic to potential energy when drawing an arrow)

    conversion is inefficient because some energy is "lost" as heat
  7. Composition of Matter

    cannot be broken down by ordinary chemical means

    • each element has unique properties:
    • physical properties = detectable with our senses, or are measurable
    • chemical properties = how atoms interact (bond) with one another
  8. Composition of Matter

    unique building blocks for each element
  9. Atomic symbol
    one or two letter chemical shorthand for each element
  10. The major elements of the human body
    • Oxygen (O)
    • Carbon (C)
    • Hydrogen (H)
    • Nitrogen (N)

    These make up about 96% of body mass
  11. Lesser elements of human body
    • These are about 3.9% of body mass:
    • Calcium (Ca)
    • Phosphorus (P)
    • Potassium (K)
    • Sulfur (S)
    • Sodium (Na)
    • Chlorine (Cl)
    • Magnesium (Mg)
    • Iodine (I)
    • Iron (Fe)
  12. Trace elements of human body
    • are typically part of enzymes
    • <0.01% of body mass:
    • Chromium (Cr)
    • Manganese (Mn)
    • Zinc (Zn)
  13. Atomic Structure
    • Determined by numbers of subatomic particles
    • nucleus consists of neutrons and protons
  14. Atomic Structure

    • Neutrons
    • No charge
    • Mass = 1 atomic mass unit (amu)
    • Protons
    • positive charge
    • mass = 1 amu
    • Electrons
    • orbit nucleus
    • equal in # to protons in atom
    • negative charge
    • 1/2000 the mass of a proton (0 amu)
  15. Models of the Atom
    • Orbital model = current model used by chemists. Depicts probable regions of greatest electron density (an electron cloud).  Useful for predicting chemical behavior of atoms.
    • Planetary model = oversimplified, outdated model. Incorrectly depicts fixed circular electron paths.  Useful for illustrations.
  16. Identifying Elements
    atoms of different elements contain different #s of subatomic particles

    • Atomic number = # protons in nucleus (periodic table)
    • Mass number = mass of the protons and neutrons
    • --- mass numbers of atoms of an element are not all identical
    • --- isotopes are structural variations of elements that differ in the number of neutrons they contain
    • Atomic weight = average of mass numbers of all isotopes
  17. Radioisotopes
    • spontaneous decay (radioactivity)
    • similar chemistry to stable isotopes
    • can be detected with scanners
    • valuable tools for biological research and medicine

    Cause damage to living tissue; useful against localized cancers; radon from uranium decay causes lung cancer
  18. Molecules and Compounds
    • Most atoms combine chemically with other atoms to form molecules and compounds
    • Molecule = two or more atoms bonded together (e.g. H2 or C6-H12-O6)
    • Compound = two or more different kinds of atoms bonded together (e.g. C6-H12-O6)
  19. Mixtures
    Most matter exists as mixtures; 2 or more components physically intermixed

    • 3 types of mixtures
    • solutions (salt water)
    • colloids (milk - fat globules dispersed in a watery solution)
    • suspensions (mud - sand suspended in water)
  20. Solutions
    • homogeneous mixtures
    • usually transparent, e.g. atmosphere, air, or seawater

    • Solvent = present in greatest amount, usually a liquid
    • Solute(s) = present in smaller amounts
  21. Concentration of Solutions
    expressed as:

    • Percent or parts per 100 parts
    • milligrams per deciliter (mg/dl)
    • molarity or moles per liter (M)
    • --- 1 mole = the atomic weight of an element or molecular weight (sum of atomic weights) of a compound in grams
    • --- 1 mole of any substance contains 6.02 x 10^23 molecules (Avogadro's number)
  22. Colloids
    colloids (emulsions)

    heterogeneous translucent mixtures (cytosol)

    large solute particles that do not settle out

    undergo sol-gel transformations
  23. Suspensions
    heterogeneous mixtures (blood)

    large, visible solutes tend to settle out, and may scatter light
  24. Mixtures vs. Compounds
    • Mixtures
    • no chemical bonding between components
    • can be separated physically, such as by straining or filtering
    • heterogeneous or homogeneous

    • Compounds
    • can be separated only by breaking bonds
    • all are homogeneous