Chemistry of Life

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Chemistry of Life
2012-01-04 17:46:07
biology chemistry Life

1st tri honors Biology 2nd test
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  1. what are all substances made out of?
  2. Define: element
    a substance that can't be broken down into simpler substances
  3. On earth, how many elements occur naturally?
  4. how many elements are essentail to living organisms?
  5. what four elements make up more than 96% of the mass of a human?
    carbon, hydrogen, oxygen, and nitrogen
  6. Each element is abbreviated by a one or two letter ________.
  7. Define: atom
    the smallest particle of an element that has the characteristics of that element
  8. what is at the center of an atom?
  9. what is the nucleus made up of?
    charged particles called protons and paricles called neutons, which have to charge
  10. All Nuclei are _______ charged because of the presence of ______.
    • Positively
    • protons
  11. what forms a cloud around the necleus?
    Are they positive or negative?
    • electrons energy levels
    • negative
  12. Define: energy levels
    where electrons travel around necleua in certain regions
  13. What is the formula that is used to figure out how many electrons an energy level can hold?
    • 2n2
    • N= the energy level
  14. Atoms contain __________ numbers of electrons and protons. Therefore, they have____ ________.
    • equal
    • no charge
  15. Define: isotopes
    atoms of the same element that have different numbers of neutrons in the nucleus
  16. Define: compound
    a substance that tis composed of atoms of different elements chemically combined.
  17. Why to atoms combine with other atoms?
    to become be stable
  18. How to atoms become more stable by combining?
    by sharing electrons
  19. Define: covalent bond
    when two atoms share electons, covalent bond is the force that holds them together
  20. define: molecule
    a group of atoms held together by covalent bonds and having no overall chrage.
  21. What two types of thing are bonding in a covalent bond?
    a nonmetal to a nonmetal
  22. Define: ion
    an atom that gains or loses electrons that has an electrical charge
  23. Define: ionic bond
    a bond formed by the mutual attraction of two ions of opposite charge.
  24. What two types of thing are bonding in an ionic bond?
    a metal to a nonmetal
  25. Ionic bonds do not form _____ _______.
    true molecule
  26. Define: mixture
    a combination of substance that don't combine chemically but retain ther individual properties
  27. Define: solution
    a mixture in which one or more substances are distributed evenly in another substance
  28. water make up ___ to ____ percent of most organisms.
    70 to 95
  29. Define: polar molecule
    a molecule with an uneaqual sidtribution of charge
  30. water is _____.
    a polar molecule
  31. Define: metabolism
    total of all chemical reactions that occur within a living organism
  32. Define: reactants
    substances that under-go chemical reactions
  33. Define: products
    substances formed by chemical reactions
  34. What is the easiest way to understand chemical reacctions?
    atoms are never created or destroyed, they are simply rearranged.
  35. Chemical equations must always be written so that they are _______.
  36. What are the five unique properties of water?
    • Universial solvent
    • High Heat Capicity
    • High Boiling and High Freezing Points
    • high surface tenison
    • expands when frozen
  37. Define: pH
    a symbol to describe how acidic or basic a solution is; the pH scale ranges from 0 to 14; a solution with a pH of 7 is neutral, above 7 is basic, and below is acidic
  38. Define: Base
    a substance that forms hydroxide ions in water; solutions with a pH of 7 or above
  39. Define: Acid
    any substance that forms hydrogen ions in water; acidic solutions have pH below 7
  40. What is a family on the periodic table?
    vertical rows
  41. What is a Period on the periodic table?
    horizontal rows
  42. I'm a ______ based life form
  43. Why is Carbon the best?
    • It has four open bonding sites
    • non-metal
    • carbon filter the best because it is so tightly bonded