Shell Model
Learning Objectives
- reproduce a shell model of an atom
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Overview
The most straightforward concept of the atom is the shell model, first proposed by Niels Bohr.
A nucleus contains protons and neutrons. Protons carry a positive charge, and neutrons carry no charge. The nucleus is surrounded by shells of negatively-charged electrons.
Each shell can only hold a fixed number of electrons, and each shell essentially represents a principal energy level. The electrons orbit around the nucleus.
(Quantum physics has shown this is more of an electron cloud, and there is a limit to how precise one can simultaneously know the position or momentum of a particle; aka the Heisenberg Uncertainty Principle. For now though, we are only concerned with the Bohr shell model.)
Example
The calcuim atom contains 20 protons and 20 neutrons.
The uranium atom contains 92 protons, the number of neutrons will be different if the atom is or .
Each electron shell is label by its principal quantum number; e.g., 1, 2, 3, 4, etc., with the lower number closer to the nucleus.
The dynamic periodic table gives a lot of information about all the elements.
Assessments
Overview
The most straightforward concept of the atom is the shell model, first proposed by Niels Bohr.
A nucleus contains protons and neutrons. Protons carry a positive charge, and neutrons carry no charge. The nucleus is surrounded by shells of negatively-charged electrons.
Each shell can only hold a fixed number of electrons, and each shell essentially represents a principal energy level. The electrons orbit around the nucleus.
(Quantum physics has shown this is more of an electron cloud, and there is a limit to how precise one can simultaneously know the position or momentum of a particle; aka the Heisenberg Uncertainty Principle. For now though, we are only concerned with the Bohr shell model.)
Example
The calcuim atom contains 20 protons and 20 neutrons.
The uranium atom contains 92 protons, the number of neutrons will be different if the atom is or .
Each electron shell is label by its principal quantum number; e.g., 1, 2, 3, 4, etc., with the lower number closer to the nucleus.
The dynamic periodic table gives a lot of information about all the elements.