http://www.ck12.org Chapter 2. Matter
A:The resulting atom represents a different element. That’s because each element has a unique number of protons.
For example, all atoms of helium have two protons. If one of the protons in a helium atom changes to a neutron, the
resulting atom would have just one proton, so the atom would no longer be a helium atom. Instead it would be a
hydrogen atom, because all hydrogen atoms have a single proton.
Summary
- The electromagnetic force of attraction between negative electrons and positive protons in the nucleus keeps
electrons in the area surrounding the nucleus. - The electromagnetic force of repulsion between positive protons in the nucleus is overcome by the strong
nuclear force between protons and neutrons. This force holds the nucleus together. - The weak nuclear force changes subatomic particles from one type to another. When protons change to
neutrons, this changes atoms of one element to atoms of a different element.
Explore More
Do the atom builder activity at the following URL. Use the activity to build a stable atom that has three protons.
Make sure you take atomic forces into account in your atom. Include enough protons and electrons to avoid creating
a charged or radioactive atom. If you need help, read the atom builder guides listed at the bottom of the Web page.
http://www.pbs.org/wgbh/aso/tryit/atom/#
Review
- Which subatomic particles are affected by electromagnetic force? How does this force affect them?
- What is the strong nuclear force? How does it hold the nucleus together?
- How does the weak nuclear force differ from the other fundamental forces inside the atom? How can it change
an atom of one element to an atom of a different element?