Transcript Electrons - Mrs. Pinnell

Electrons
and the Bohr Model
Neils Bohr
• Neils Bohr was convinced that the atom could
be pictured as a small positive nucleus with
electrons orbiting around it as the planets
orbit the sun.
The Bohr Model
• Neils Bohr pictured the electron moving in
circular orbits corresponding to the various
allowed energy levels.
Bohr proved incorrect
• Although the Bohr model paved the way for
later theories, it is important to realize that the
current theory of atomic structure is not the
same as the Bohr model.
• Electrons do NOT move around the nucleus in
circular orbits like planets orbiting the sun.
• Bohr’s model is useful (in the chemistry
classroom) for picturing the electrons present in
an atom.
The Bohr Model – in use
• The Bohr model does NOT focus on the
nucleus, but rather on the electrons.
• The electrons are first placed on the
innermost electron shell or energy level.
• Two electrons can fit in this level.
The Bohr Model – in use (cont.)
• The electrons are then placed on the second
electron shell or energy level.
• Eight electrons can fit in this level.
• The electrons are
then placed on the
third electron shell or
energy level.
• 18 electrons can fit
in this level.
The Bohr Model – in use (cont.)
• Electrons are represented by dots.
• Electrons are usually placed singly at first and
then doubly.
• Example: Sodium
Let’s try one…
• Example: Sulfur