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The Electron
Unit: Electronic Structure
Knowledge/Understanding:

facts about electrons

the particle/wave nature of electrons
electron: a small subatomic particle found outside the nucleus of an atom.
mass
= 9.11 × 10−31 kg = 9.11 × 10−28 g
= 1/1836 of the mass of a proton
charge
= −1.6022 × 10−19 coulomb
= −1 elementary charge
radius
= 2.8179 × 10−15 m
electric current (electricity): electrons moving from one place to another.
Protons and neutrons remain in the nucleus of their atom (except for nuclear
decay), but electrons can be removed from one atom and added to another.
ion: an atom (or group of atoms that functions like a single atom) that has an
electric charge because it has either gained or lost electrons.
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Chemistry I
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The Electron
Because an electron has mass (though it’s very small—about 1/1836 of the
mass of a proton or neutron), this means electrons are particles, and all of
the equations that apply to motion of solid particles also apply to electrons.
However, an electromagnetic wave is a wave of electricity, and electricity is
made of electrons that are moving. This means that moving electrons are
also waves—they move through empty space, carrying energy with them.
Therefore, all of the equations that apply to waves also apply to electrons.
This means that an electron must be both a wave and a particle at the same
time.
quantum: a discrete increment (plural: quanta) If a quantity is quantized, it
means that only certain values for that quantity are possible.
Because an electron behaves like a wave, it can only absorb energy in
quanta that correspond to exact multiples of its wavelength.
Neils Bohr: was the firslt to realize that atomic spectral emissions are
quantized, which means electron energy levels must also be quantized.
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Chemistry I
Mr. Bigler
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The Electron
Rutherford-Bohr model: a model
of the atom in which the distance
from the nucleus to an electron
equals the electron’s (quantum)
energy level. Sometimes called
the “planetary model” because it
looks like a solar system, with
the nucleus in place of the sun
and electrons in place of the
planets.
What actually happens is not that
simple. If an electron is in the
first energy level (n = 1), the
Bohr model may predict its
average distance from the
nucleus, but the electron is also a
particle, so it has some freedom
to move closer or farther. If we
took several pictures of the one
electron in a hydrogen atom over
a period of time, it might look
like this:
It would be more accurate to say that the electron has a high probability
of being found inside a region with the radius that corresponds to the
first energy level (n = 1).
Use this space for additional notes.
Chemistry I
Mr. Bigler
Page 3 of 3