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# Comparison of Numbers in Scientific Notation

## Use <, > and/or equal to when comparing values written in scientific notation.

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Practice Comparison of Numbers in Scientific Notation
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On an Atomic Scale

Credit: Dartmouth Electron Microscope Facility/Dartmouth College
Source: http://commons.wikimedia.org/wiki/File:Misc_pollen.jpg

Have you ever used a microscope? A microscope can magnify objects and creatures that are invisible to the naked eye. With a good microscope, you can watch single-celled organisms grow and move. But what if you wanted to see something smaller, such as individual molecules? A regular light microscope wouldn’t be able to help you. If you want to see things on that scale, you need an electron microscope.

#### Scanning and Tunneling

Electron microscopes bounce a tight beam of electrons off a sample. The electrons react with the atoms in the sample. The microscope then records these reactions and uses them to create a picture. Electron microscopes are incredibly accurate. They can measure features that are only 2×1010\begin{align*}2 \times 10^{-10}\end{align*} meters across, whereas light microscopes can only measure down to a scale of 1×107\begin{align*}1 \times 10^{-7}\end{align*} meters. With electron microscopes, scientists can see viruses and bacteria. They can examine how crystals form. They can observe how various materials look at the molecular level and then use this information to create new materials. In 2012, scientists in Italy used an electron microscope to get a clear picture of a strand of DNA.

Credit: Idaho National Laboratory
Source: http://www.flickr.com/photos/inl/9086814101/

Electron microscopes are great tools, but your school probably won’t get one anytime soon. These microscopes need to be maintained in a special laboratory setting in order for them to take clear pictures. They are also very expensive and require a lot of electricity to run. However, you can enjoy photos from electron microscopes on the Internet. They’re a great way to learn about the world around us.

#### Explore More

Watch the videos below to see electron microscopes in action.

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