<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation
We are experiencing issues with our servers. While we work to resolve these issues, assignments will not be available on your dashboard. They can be accessed via your groups.
You are viewing an older version of this Concept. Go to the latest version.

Bohr Model of the Atom

Also known as the planetary model, electrons are organized into energy levels with the nucleus at the center.

Atoms Practice
Estimated1 minsto complete
Practice Bohr Model of the Atom
Estimated1 minsto complete
Practice Now
Turn In
Scanning Tunneling Microscopy

Scanning Tunneling Microscopy

Credit: Taner Yildirim (The National Institute of Standards and Technology - NIST)
Source: http://en.wikipedia.org/wiki/File:Chiraltube.gif
License: CC BY-NC 3.0

A scanning tunneling microscope is used to see surfaces at the atomic level. Seen above is a chiral nanotube seen in STM experiments.

Amazing But True

  • One of the methods currently available to scientists to image individual atoms is done so by a scanning tunneling microscope. The STM works on the concept of quantum tunneling. To understand quantum tunneling, you need to first understand what happens classically with electrons in metals. Classically, the loosest electrons in metals are always held in the metal unless given enough energy which is defined by the work function. If the electrons are not given energy greater than the work function, they are not knocked loss.
  • When looked at quantum mechanically though, it is possible for the loosest bound electrons to tunnel through the barrier in less energy than that required to leave the metal. By placing two pieces of metal together, a finite well is created where the most weakly bound electrons have a probability of tunneling through the energy barrier given by .
  • By using a very small electrically charged probe, you can monitor the electrical current and plot where atoms are located on the surface of a metal. This is how a scanning tunneling microscope works.


Explore More

Using the information provided above, answer the following questions.

  1. Why don't we see objects tunnel through walls in our everyday life?
  2. Why can't someone use a regular microscope to view atoms?

Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes
Please to create your own Highlights / Notes
Show More

Image Attributions

  1. [1]^ Credit: Taner Yildirim (The National Institute of Standards and Technology - NIST); Source: http://en.wikipedia.org/wiki/File:Chiraltube.gif; License: CC BY-NC 3.0

Explore More

Sign in to explore more, including practice questions and solutions for Bohr Model of the Atom.
Please wait...
Please wait...