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2010-12-01 01:12:01
Chemical Context LIfe

Ch. 2
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  1. matter
    anything that takes up space and has mass (dead or living); matter is made up of elements
  2. elements
    • is a substance that cannot be
    • broken down to other substances by chemical reactions (its made up of one type
    • of atom);
    • there are 92 elements
    • occurring in nature
  3. compound
    a substance consisting of two or more diff. elements combined in a fixed ratio ex: NaCl (table salt)
  4. trace elements
    • are those required by an organism only in
    • minute quantities like Ca P K S
  5. atom
    • smallest unit of matter that still retains the properties of an
    • element
  6. neutrons
    no electrical charge
  7. protons
    positive charge
  8. electrons
    negative charge
  9. atomic number
    # of protons
  10. mass number
    sum of protons plus neutrons in the nucleus
  11. isotopes
    different atomic mass but same element
  12. radioactive isotopes
    • one which the nucleus decays
    • spontaneously, giving off particles and energy
  13. energy
    the capacity to cause change
  14. electron shells
    • charac. Avg. distance and
    • energy level; The chem. Behavior of an atom depends mostly on the number of electrons in its outermost shell
  15. inert
    means that the atom is not chemically reactive
  16. orbital
    the 3-D space where an electron is found 90% of the time
  17. covalent bond
    sharing a pair of valance electrons by two atoms
  18. molecule
    two or more atoms held together by covalent bonds
  19. Lewis dot structure
    • H:H ( 2 hydrogen covalent
    • bond); Molecular formula: H2
  20. electronegativity
    • the attraction of particular kind of atom
    • for the electrons of a covalent bond
  21. non polar covalent bond
    electrons are shared equally
  22. polar covalent
    • bond are not shared equally
    • Oxygen has a partial negative atom “delta minus”
    • Hydrogen has a partial positive atom “delta plus”
  23. ion
    charged molecule or atom
  24. cation
    positive charged ion
  25. anion
    negative charged ion
  26. ionic bond
    when cation and anion attract each other. Opposite attraction Ionic compounds or salt: compounds formed by ionic bonds; Most strongest bond is covalent bond
  27. hydrogen bond
    weak chem. Bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom
  28. van de waals interaction
    weak and occur only when atoms and molecules are very close together