The Bohr Model and Diagram

Bohr (1920’s)

·  Rutherford’s model was inherently unstable because Protons and electrons should attract each other.

·  Matter emits light when it is heated (Blackbody Radiation).

·  Light travels as protons.

·  Energy photons carry depends on their wave length.

· Bohr based his model on energy (Light) that is emitted by different atoms.

·  Each atom has a specific spectrum of light.

·  To explain the emissions spectrum, Bohr suggested that electrons occupy shells or orbits

·  High Proton energy = Purple

·  Low Photon energy = Blue

·  Electrons exist in an orbital. When they absorb energy they move to a higher orbital.

·  As they fall from a higher orbital to a lower orbital they release energy as a photon of light.

The Bohr Model and Diagram:

• Atoms are neutral and Ions have different charges
• 1^st shell holds 2 electrons
• 2^nd shell holds 8 electrons
• 3^rd shell holds 8 electrons
• 4^th shell holds 16 electrons
• A full octet is always wanted
• The last shell is called a “Valence Shell” and the electron in that shell are called “Valence Electrons”

Bohr Model:

• Atoms are electrically neutral
• Two different models can be used to describe electron configuration:

1.    Energy Level Model

2.    Bohr Model