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  Atoms and Electrons

Energy and Work

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Atoms

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helium atomAtoms are the building blocks of everything around us, including our earth, the sun, and all other planets in the universe. Amazingly, there are just over 100 types of atoms that make up all matter. Each type of atom has a particular number of protons and electrons. It is the number of protons that makes each type of atom unique. (Each unique type of atom is called an element.)

Parts of an Atom
Atoms are made up of three main parts: neutrons, protons, and electrons. The neutrons and protons join together to form the nucleus of an atom. The electrons spin around the nucleus.

Check it Out!
Fifty million atoms lined up would measure one millimeter long.

Charged Particles
Protons and electrons are very interesting. They carry a charge. That is, they are either attracted to or repelled by each other. Protons carry a positive charge. Electrons carry a negative charge. Neutrons don't carry any charge; they are neutral. Opposite charges attract. Like charges repel. A neutral charge will pair up with both.

opposite charges

 

like charges

 

neutrons

The charges are what allow the electron to spin in orbit around the nucleus. The electrons are attracted to the nucleus because the positively charged protons are there.

Radioactive Atoms
Some atoms are unstable. The nucleus has too many or too few protons. Sometimes this will cause the atom to shoot out part of its nucleus in the form of radiation. These particles of radiation are gamma rays, beta particles, and alpha particles.

Physical Properties
Alpha particles contain two protons and two neutrons. Beta particles are electrons. Gamma rays are invisible rays (like X-Rays).

radiation

 

radiation shields
Blocking Radiation
Of the three types of radiation, beta particles and gamma rays are dangerous to humans and other organisms. Beta particles can be stopped by a sheet of aluminum. Gamma rays can be stopped by a thick sheet of lead or concrete. Alpha particles are stopped by paper.

Uses of Radiation
Radioactive elements are used to generate nuclear energy and to create nuclear weapons. It takes very little of a radioactive element to produce a lot of energy.

Periodic Table of Elements
Check out the different types of atoms that make up our universe with the interactive Periodic Table of Elements on the Los Alamos National Laboratory's Chemistry Division Web site.

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