Bio 2.txt

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Bio 2.txt
2012-01-08 02:06:39
bio chapter

bio chapter 2
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  1. Matter
    Anything that occupies space and has mass
  2. Element
    • Substance that can't be broken down further
    • 92 natural elements, several synthetic elements
  3. Compound
    2+ elements combined in a fixed ratio
  4. Trace elements
    • There are 25 elements essential to life- oxygen, carbon, nitrogen a hydrogen make up 96.3% and 7 other elements make up 3.7%
    • The other 14 elements are essential only in minute quantities
  5. Atom
    Smallest unit of matter that still behaves like an element
  6. Proton
    Subatomic particle with a positive charge
  7. Electron
    Subatomic particle with a negative charge
  8. Neutron
    Subatomic particle with no charge
  9. Nucleus
    • An atom's central core
    • Consists of protons and neutrons
  10. Atomic number
    All atoms have a specific number of proteins unique to their element
  11. Mass number
    Sum of the protons and neutrons
  12. Atomic mass
    Very similar to mass number but has the weight of electrons too
  13. Isotopes
    Atoms of the same element with different numbers of neutrons
  14. Radioactive isotope
    • An atom's nucleus decays spontaneously
    • Gives off particles and radiation
  15. Electron shells
    Electrons move around an atom's nucleus at certain energy levels- the shells
  16. Chemical bonds
    Attractions that hold atoms together
  17. Covalent bond
    Bond where atoms share electrons
  18. Molecule
    2+ atoms held together by covalent bonds
  19. Electronegativity
    An atom's attraction for shared electrons
  20. Nonpolar covalent bonds
    Electrons are shared equally between atoms
  21. Polar covalent bond
    • Unequal sharing of electrons
    • One atom partially positive one slightly negative
    • Water
  22. Polar molecule
    A molecule with unequal distribution of charges
  23. Ion
    Atom/molecule with an electrical charge because they lost or gained an electron
  24. Ionic bond
    2 ions with opposite charges attracted and held together
  25. Salt
    Ionic compound
  26. Hydrogen bond
    • Weak but very important
    • Partial positive hydrogen atoms attract to nearby negative atoms
  27. Chemical reaction
    • Breaking and making of chemical bonds
    • Change the composition of matter
  28. Reactants
    Starting material in chemical reactions
  29. Products
    Material that results from chemical reactions
  30. Cohesion
    • Molecules of the same kind stick together
    • Stronger for water
  31. Adhesion
    One substance clinging to another
  32. Heat
    Amount of energy associated with the movement of atoms
  33. Temperature
    Measures the intensity of heat
  34. Evaporative cooling
    • When a substance evaporates, the surface is left cooler than before
    • Greatest energy leaves so lower energy and lower temp remain behind
  35. Solution
    Liquid with a uniform mixture of 2+ substances
  36. Solvent
    Dissolving agent
  37. Solute
    • Substance that is dissolved
    • Usually a salt
  38. Aqueous solution
    Water is the solvent of a solution
  39. Acid
    Donates hydrogen atoms to solutions
  40. Base
    Removes hydrogens from a solution
  41. pH scale
    Describes how acidic or basic a solution is
  42. Buffers
    Minimize changes in pH to sustain life
  43. Acid precipitation
    Rain snow or fog with a pH lower than 5.2
  44. Ocean acidification
    • Carbon dioxide dissolves in seawater and lowers pH
    • Produces carbonic acid