Radioactivity occurs when the strong force holding the nucleus of an atom together is not strong enough, causing the nucleus to decay and emit matter and energy. The strong force attracts protons and neutrons together in the nucleus, while the electric force normally causes protons to repel each other. Isotopes are nuclei with the same number of protons but different numbers of neutrons, which can be created through radioactive decay. The radioactive half-life is the amount of time it takes for half of the nuclei in an isotope sample to decay.

1. Radioactivity

2. Protons (p + ) and neutrons (n 0 ) make up the nucleus of an atom. Strong force- force that causes protons and neutrons to be attracted to one another. -It is a short-ranged force that becomes weak as distance increases.

3. Electric force- force that normally causes protons to repel from each other. -It is a long-ranged force that causes the repulsion as distance increases.

4. Protons together + + Strong Force Electric Force Total Force Protons apart + + No Strong Force Electric Force Total Force

5. Radioactivity - when the strong force is not large enough to hold a nucleus together, the nucleus can decay and give off matter and energy.

6. Isotopes- nucleus with the same number of protons but different number of neutrons. This is due to radioactivity. Ex: Carbon Carbon-14 6 protons 6 protons 6 neutrons 8 neutrons Not an isotope Isotope

7. Radioactive half-life = amount of time it takes for half of the nucleus in an isotope to decay. Ex: Carbon-14 5730 yrs. Polonium-211 0.5 sec Uranium-238 4.5 bill yrs.