Question:
s it true that the exact nature of electrons inside the atom is
not yet known? If this is true, why are students in physics and chemistry
continually shown the model of the atom that depicts electrons as discrete
particles orbiting at various distances from a nucleus without even being told
that this model is completely incorrect?
Replies:
A lot about electrons in atoms is known very well. We know that
electrons are point particles that have a charge, a mass, and an intrinsic
spin. We know the equations that specify the probability of our finding the
electrons if we were to look for them. We know the energies that the
electrons will have in those states. We cannot find the electrons position
exactly because they are so light that any probe we would use would disrupt
them and destroy our knowledge about where they were. That means that we must
use quantum mechanics which only allows us to find out where it is likely to
find the electrons. Measurements of these probabilities (wave functions) and
energies have been confirmed to great accuracy for simple systems where we can
do the calculations can be done exactly. For more complex systems, we cannot
carry out the calculations quite as accurately, but the results we get are
very accurate and let us make many predictions. We know a lot. The pictures
students see often make it look like we can determine where the particles are
when we cannot, but we can determine the energy and wave function so well that
we really know about all that we can know about such small particles.
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.
