2.29. Atomic Nucleus http://www.ck12.org
nuclear force—holds protons and neutrons together in the nucleus. You can learn more about these forces in the
nucleus by watching the video at this URL:
http://www.youtube.com/watch?v=PdFsb2sWrW4 (6:27)
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/54908Q:Can you guess why an atomic bomb releases so much energy when it explodes?
A:When an atomic bomb explodes, the nuclei of atoms undergo a process called fission, in which they split apart.
This releases the huge amount of energy that was holding together subatomic particles in the nucleus.
Summary
- The nucleus is a small, dense region at the center of the atom. It consists of positive protons and neutral
neutrons, so it has an overall positive charge. - The nucleus is just a tiny part of the atom, but it contains virtually all of the atom’s mass.
- The strong nuclear force holds together protons and neutrons in the nucleus and overcomes the electric force
of repulsion between protons.
Vocabulary
- nucleus: Tiny region in the center of an atom that contains protons and neutrons and makes up almost all of
the atom’s mass.
Explore More
Watch this short video about how the nucleus was discovered, and then answer the questions below.
http://www.youtube.com/watch?v=Q8RuO2ekNGw (0:48)
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/54909- Describe the scientific procedure that was used to discover the nucleus.
- What evidence led scientists to conclude that atoms consist mostly of empty space with a very small, positively
charged mass at the center? - Reflect on the method used in the experiment. Why was it important to send positive—as opposed to neutral
or negative—particles toward the gold foil?