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Section 4.4 Unstable Nuclei and Radioactive Decay.

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Presentation on theme: "Section 4.4 Unstable Nuclei and Radioactive Decay."— Presentation transcript:

1 Section 4.4 Unstable Nuclei and Radioactive Decay

2 Objectives Explain relationship between unstable nuclei and radioactive decay Characterize alpha, beta, and gamma radiation in terms of mass and change

3 Review Recall chemical reactions –Are new substances formed? –Were atoms affected/changed? Chemical reactions only involve electrons Nucleus is NOT affected in CHEMICAL REACTIONS

4 Nuclear Reactions DO change the nucleus Atoms of one element change into atoms of another

5 Radioactivity Substance spontaneously emits radiation Rays and particles are called radiation Atoms change into other elements

6 Unstable Systems Radioactivity occurs when an atom’s nucleus is unstable Unstable systems gain stability by losing energy

7 Radioactive Decay Unstable nucleus loses energy by emitting radiation spontaneously Radiates until stable New atom forms

8 Types of Radiation Alpha Beta Gamma

9 Alpha Radiation Deflects toward a negative charge Alpha particles 2 protons & 2 neutrons 4 2 He or  Blocked by only a thin sheet of paper

10 Nuclear Equation Ra  Rn He Radium Radon

11 Beta Radiation Deflect toward positive charge Beta particles,  Electron (-1 charge) Aluminum blocks beta radiation 14 6 C  14 7 N 

12 Gamma Radiation High energy radiation No mass No charge Most dangerous Accompany  or  particles Account for energy lost CANNOT form new atom on its own 0 0 

13 Characteristics of Radiation Types RadiationSymbolMass (amu) Charge Alpha  42+ Beta  1/ Gamma  00




17 Practice Co  Ni + ____ Am  ____ He

18 Practice Solution Complete the following nuclear reactions: Co  Ni  Am  Np He

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