TCC Biology Class

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TCC Biology Class
2014-09-02 19:48:59
Chapter 2
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  1. What is an Element
    is a substance that cannot be broken down to other substances by chemical reactions.
  2. Compound
    is a substance consisting of two or more different elements combined in a fixed ration.
  3. Essential Elements
    Of the 92 natural elements, about 20-25% are essential elements that an organism needs to live a healthy life and reproduce.
  4. Trace Elements
    are required by an organism in only minute quantities. Some trace elements, such iron are needed by all forms of life, others are required only by certain species.
  5. Atom
    is the smallest unit of matter that still retains the properties of an element.
  6. Dalton
    A unit of measurement for atoms and subatomic particles.
  7. Atomic number
    the number of protons
  8. Mass Number
    the number of neutrons
  9. Isotopes
    the difference between atomic forms of the same element are called isotopes of the element.
  10. Atomic mass
    because neutorns and protons each have a mass very close to 1 Dalton, the mass number is an approximation of the total mass of an atom.
  11. Radioactive Isotope
    is one in which the nucleus decays spontaneously, giving off particles and energy.
  12. Energy
    is defined as the capacity to cause change-for instance by doing work