Science - 2017-18

PS.3 - Atomic Structure

The student will investigate and understand the modern and historical models of atomic structure. Key concepts include

a) the contributions of Dalton, Thomson, Rutherford, and Bohr in understanding the atom; and

b) the modern model of atomic structure.

Bloom's Levels:  Analyze; Understand

Adopted: 2010


  • Atoms are the building blocks of matter.

  • I can communicate how the model of the atom has changed over time.


  • Many scientists have contributed to our understanding of atomic structure.
  • The atom is the basic building block of matter and consists of subatomic particles (proton, neutron, electron, and quark) that differ in their location, charge, and relative mass. Protons and neutrons are made up of smaller particles called quarks. 
  • Size at the atomic level is measured on the nanoscale. 
  • Scientists use models to help explain the structure of the atom. Their understanding of the structure of the atom continues to evolve. Two models commonly used are the Bohr and the “electron cloud” (Quantum Mechanics) models. The Bohr model does not depict the three-dimensional aspect of an atom, and it implies that electrons are in static orbits. The “electron cloud” model better represents our current understanding of the structure of the atom.


In order to meet this standard, it is expected that students will

a)  describe the historical development of the concept of the atom and the contributions of Dalton, Thomson, Rutherford, Bohr and other scientists (Schrödinger).

     compare the Bohr atomic model to the electron cloud model with respect to its ability to represent accurately the three-dimensional structure of the atom.

b)  differentiate among the three basic particles in the atom (proton, neutron, and electron) and their charges, relative masses, and locations.


atom, proton, neutron, electron, quantum mechanics, electron cloud

Updated: Nov 24, 2017