Electrons and the Bohr Model Neils Bohr Neils

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

Practice • Example : Sulfur