Radioactivity

The Strong Force

• Nucleons are bound together by the strong force
• It is the strongest force in the Universe
• Aka Strong Nuclear Force
• It is effective over extremely short distances
• Protons want to repel each other
• Neutrons help to keep the protons from repelling out of the nucleus
• Neutrons also carry the Strong force

Light elements usually only need equal number of protons as neutrons

• Light elements usually only need equal number of protons as neutrons
• Ex: Carbon’s most common form has 6 protons and 6 neutrons
• Heavier elements need more neutrons than protons to hold the nucleus together.
• Ex: Lead’s most common form has 82 protons and 126 neutrons
• For elements with MORE than 83 protons, they remain unstable no matter how many neutrons are added.

Check Your Understanding

• What is the weakest force in the universe?
• Gravity
• What is the strongest force in the universe?
• The strong force (or strong nuclear force)
• If the strong nuclear force is so strong, why do we feel gravity more?
• B/c gravity has a much longer range than the strong force. The strong force only extends as far as an atom’s nucleus.
• BrainPop Radioactivity

Radioactive Decay

• Atoms can be stable or unstable
• If they are unstable, they try to change their number of protons, neutrons, or electrons to make themselves more stable

Radioactive: term applied to an atom with a nucleus that is unstable and that can spontaneously emit a particle and become the nucleus of another type of atom

• Radioactive: term applied to an atom with a nucleus that is unstable and that can spontaneously emit a particle and become the nucleus of another type of atom
• All elements with more than 83 protons will decay…so they are radioactive