http://www.ck12.org Chapter 2. Matter
2.31 Neutrons
- Describe neutrons.
- Explain how isotopes of an element differ from one another.
- Identify fundamental particles in neutrons.
The arrow in this photo is pointing to a star that doesn’t look like much compared with some of the other stars in the
picture. It’s certainly much smaller than most other stars. In fact, it’s only about 20 kilometers in diameter. Compare
that with the 1.4-million-kilometer diameter of our own sun. Despite its small size, however, this star has greater
mass than the sun, making it incredibly dense. It also has tremendous gravity. In fact, gravity on its surface is about
2 × 1011 times the gravity we feel on Earth! What type of star is it? It’s called a neutron star. That’s because it
consists solely of neutrons. You can learn more about these fascinating stars at the URL below. You will read about
neutrons in this article.
http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html
What Is a Neutron?
Aneutronis one of three main particles that make up the atom. The other two particles are the proton and electron.
Atoms of all elements—except for most atoms of hydrogen—have neutrons in their nucleus. The nucleus is the
small, dense region at the center of an atom where protons are also found. Atoms generally have about the same
number of neutrons as protons. For example, all carbon atoms have six protons and most also have six neutrons.
A model of a carbon atom is shown in theFigure2.56. For an excellent video explaining the structure of atoms,
including neutrons, go to this URL: