Nuclear Decay Song on Youtube   Animation of Alpha, Beta, Gamma rays on youtube radioactive dating using Uranium on Youtube Animation Explain Why Nuclear decay and emissions occurs One Half-life to Live Song on Youtube

2. Nuclear Radioactivity: a. Nucleus- composed of protons and neutrons b. Strong Force – causes protons and neutrons to be attracted to each other

c. Powerful only when protons and neutrons closely packed together d. Large nucleus is held less tightly than a small nucleus

3. Nuclear Decay which happens when the strong force is not large enough to hold the nucleus together a. The nucleus gives off matter and energy until they transform into a different isotope or another element

4. Isotopes  atoms with the same number of protons, but different number of neutrons Carbon-14 6 protons, 8 neutrons Carbon-12 6 protons, 6 neutrons

Stability 5. An atom’s stability will depend on the ratio of protons to neutrons in the nucleus a. A nucleus with either too many or to few neutrons compared to protons is radioactive

Explain why nuclear decay occurs. 6. POP QUIZ Explain why nuclear decay occurs.

7. History: a. 1896 – Henri Becquerel discovered radioactivity with the element Uranium

b. 1898 – Marie and Pierre Curie discovered radioactive Polonium and Radium

8. Nuclear Radiation - Particles and energy released from decaying nucleus There are 3 types: a. Alpha particles (a) b. Beta particles (b) c. Gamma rays (g)

9. Alpha Particles consists of two protons and two neutrons with an electric charge of +2. They do not travel far due to size and charge. Though they are the least penetrating form of radiation, they can cause serious damage.

Beta Particles (b): electron emitted during the radioactive decay of a neutron into a proton in an unstable nucleus. They can travel farther and faster than alpha particles because beta particles are so small.

11. Gamma Rays (g): high energy electromagnetic radiation emitted by a nucleus during radioactive decay. They have no mass and no charge. These rays can penetrate matter deeply, even buildings.

12. What are the three types of decay we walked about? Alpha, beta, gamma

13. When an atom is radioactive, it is… Unstable due to the number of neutrons, and will decay

14. Half-life of radioactive Isotopes The length of time it takes half of the atoms of a sample of the radioactive isotope to decay Varies from fractions of a second to billions of years Do you remember Plutonium’s half-life? 24,000 yrs

15. How can we use radioactive half-lives? Can be used to determine the age of old objects, such as: Fossils Rocks Artifacts

16. Rate of Nuclear Decay There are two ways to determine the rate of decay. The first is by the rate at which the mass of the radioactive isotope decreases. The second is by the rate at which the radiation (alpha and beta) is detected. (counts per minute on the Geiger counter) The half life is a constant that is dependent on the isotope, time of half life does not change over time.

Rate of Nuclear Decay

Rate of Nuclear Decay Archaeologists use half calculations to determine the age of relics and ancient bodies of humans and animals All living substances contain carbon – 14 whether they are living or dead. When the decay counts per minute of carbon -14 are compared with living materials the scientists are able to estimate their age. Some material have a half life less than one second while other may take over 100 million years to decay.

Measuring Radioactivity One can use a device like this Geiger counter to measure the amount of activity present in a radioactive sample. The ionizing radiation creates ions, which conduct a current that is detected by the instrument. Types of ionizing radiation include alpha and beta decay

17. Nuclear fission process of splitting a nucleus into two nuclei with smaller masses

18. Chain reaction – an ongoing series of Fission reactions

19. Nuclear Fusion Two nuclei with low masses are combined to form one larger nucleus

Can only happen when nuclei are moving fast Temperature must be high as the temperature of a star

20. Nuclear Notation

U Th He I Xe e 21. Nuclear Reactions + + When an atom undergoes nuclear decay it alters the make up of the nucleus. It will convert to a new element. Alpha particle decrease the atomic number by 2 and the mass number by 4 Beta particles increase the atomic number by 1 and cause the mass number to remain unchanged. U 238 92  Th 234 90 He 4 2 + I 131 53 Xe 54  + e −1