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basic science questions

Discussion in 'MCAT: Medical College Admissions Test' started by jaboy, May 24, 2002.

  1. jaboy

    jaboy Senior Member
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    I feel really stupid, but here are some questions I have:

    What keeps electrons away from he nucleus(protons) of an atom? It would seem like the attractive force would pull them together.

    What is a good book to read regarding basic atomic theory? I realized that I am memorizing a lot of stuff because I don't understand...
     
  2. isidella

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    Try the BETZ prep guide. It gives a nice amount of detail that is sufficient for a basic understanding. As for what keeps electrons where they are, my best guess is orbitals (The equation describing the probability of where an electron is at any point in time). I personally used the BELIEVE button for studing atomic theory; believe first, understand later. Good luck.
     
  3. wgu

    wgu Senior Member
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    "What keeps electrons away from he nucleus(protons) of an atom? It would seem like the attractive force would pull them together. "

    Asking for more depth is great! I'm going to make a guess here so if any physics majors out there think it is wrong- it probably is, but here goes...
    I think you're seeing two opposites of a magnet attract. That analogy is good, but think about this: if a satellite is orbiting Earth, what keeps it from crashing? There's a constant acceleration into the Earth but all that does is keep the satellite from sailing off. The satellite also has a potential energy. In my analogy if the satellite lost potential energy by approaching earth, it should gain speed. But electron can't do that, they hold a constant speed (errr I think- speed of light??). So if an electron was to lower its energy it must eject out energy (say in the form of radiation). Anyway that is the basic jest, I have no idea about the math behind all of my freethinking. :D Hope that helps!
     
  4. laviddee

    laviddee Senior Member
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    i think you're on the right track. what it comes down to is that you don't need to know why an electron stays away from the nucleus. Just be sure you know that there are different orbitals, and each orbital corresponds to a certain energy level. An e- in an outer orbital is easier to remove than one on the inner it takes less energy to remove that e-. the Kinds of questions you'll get on the mcat are ones that ask what is the e- ionization energy-- meaning the energy required to remove the e- from the atom altogether. Usually there'll be a diagram which shows each orbital labeled with a certain energy in eV.

    Also if you do want to use the satellite analogy- my guess is that it's b/c e- are always moving (not at the speed of light) but they are moving fast. Fast enough that it can overcome the centripetal acceleration towards the inside of the circle. If e- stopped moving, it would fall to the center.
     
  5. missbonnie

    missbonnie floating
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    </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by wgu:
    <strong>"this: if a satellite is orbiting Earth, what keeps it from crashing? There's a constant acceleration into the Earth but all that does is keep the satellite from sailing off. The satellite also has a potential energy. In my analogy if the satellite lost potential energy by approaching earth, it should gain speed. But electron can't do that, they hold a constant speed (errr I think- speed of light??). So if an electron was to lower its energy it must eject out energy (say in the form of radiation). Anyway that is the basic jest, I have no idea about the math behind all of my freethinking. :D Hope that helps!</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">satellites stay in orbit and do not fall down because although they are are constantly falling into the earth (due to gravity, the centripetal force), they are also moving very fast, so they are basically always "missing"just ctrashing into the earth. This also explains why things "float" in satellites, they aren't really floating (gravity due to earth is still quite strong at that distance), they are constantly falling.
     
  6. Catalyst

    Catalyst Enjoying Life
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    Electrons stay far away from the nucleus as a result of the balance between the attractive forces towards the nucleus and the repulsive forces between each other. The attractive force is what causes electrons close to the nucleus to be so close to the nucleus. However, as the number of electrons increases, so does the effect of electrons on each other. Electrons closest to the nucleus effectively "shield" other electrons from the nucleus's attractive force by blocking the nucleus's positive charge from reaching the other electrons. The positive charge is already involved in attracting to the closest electrons and thus cannot reach other electrons, causing them to be further away from the nucleus. Then, to add to the situation, electrons have repulsions among themselves, causing the distance form the nucleus to be increased as electrons repel each other.

    I hope this verbose explanation helps :) ..

    Sachin
     

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