Aim: What are the two types of Nuclear Reactions?Do Now:1. Get into your groups and compare your answers to your homework.

Nuclear Energy

• In nuclear reaction, mass is converted into energy; there is no conservation of mass.•Two types of nuclear reactions• Fission • Fusion

Nuclear Fission•Occurs when one atom absorbs a neutron and splits into two or more pieces, giving off tremendous amount of energy.

• In a fission reaction, the sum of the masses of the pieces formed is less than the mass of the original heavier piece, because some mass is converted into energy.

Fission of Uranium•When U-235 goes through fission, it releases 3 neutrons.

Those neutrons bombard other U-235 causing a chain reaction.

• The atomic bomb is an uncontrolled chain reaction.• A fission chain reaction can be

controlled in a nuclear reactor, used in some power plants to make electricity.

Nuclear Reactor

• In a nuclear power plant, heat is created in the nuclear reactor through nuclear fission. The heat is then used to turn water into steam which is used to drive the generators to produce electricity

Nuclear Fusion

•Nuclear fusion is the joining (or fusing) of the nuclei of two atoms to form a single heavier atom. •At extremely high temperatures and high pressure,

the nuclei (positively charged) can readily combine to form heavier elements and in the process release considerable energy.• This reaction occurs on the sun.

Nuclear Fusion

• The mass of the nucleus formed after fusion is less than the sum of the mass of the two substances fused, because some mass is converted to energy.• The energy generated in a fusion reaction is greater

than the energy generation in a fission reaction.

Nuclear Fusion of Nuclei of Isotopes of Hydrogen

Deuterium Tritium Helium Neutron

Fission Fusion

• Reactions produce energy.

• Mass is converted into energy

• Nucleus splits • Nuclei unite- gives much more energy than fission.

Radioactive IsotopesBenefits1. Tracers2. Medical: radioactive iodine can be

used to diagnose and treat thyroid.3. Food can be stored longer.4. Nuclear Power5. Radioactive dating

1. U-238 and Pb-206 are used for geological dating.

2. C-14 used for dating living material.

Risks

1. Biological Damage: damage or destroy cells2. Long Term Storage3. Accidents: nuclear explosion4. Pollution: nuclear waste

1. In a fusion reaction, reacting nuclei must collide. Collisions between two nuclei are difficult to achieve because the nuclei areA. both negatively charged and repel each otherB. both positively charged and repel each otherC. oppositely charged and attract each otherD. oppositely charged and repel each other

2. Given the fusion reaction: 2 1 H + 2 1H X + energy Which particle is represented by X? A. 1 1H B. 3 2He C. 3 1H D. 4 2He

3. Which change takes place in a nuclear fusion reaction?A. Matter is converted to energy.B. Energy is converted to matter.C. Ionic bonds are converted to covalent bonds.D. Covalent bonds are converted to ionic bonds.

4. Nuclear fusion differs from nuclear fission because nuclearfusion reactionsA. form heavier isotopes from lighter isotopesB. form lighter isotopes from heavier isotopesC. convert mass to energyD. convert ener gy to mass

5. A nuclear fission reaction and a nuclear fusion reaction aresimilar because both reactionsA. form heavy nuclides from light nuclidesB. form light nuclides from heavy nuclidesC. release a large amount of energyD. absorb a large amount of energy

6. In which reaction is mass converted to energy by the process of fission? A. 14 7 N + 1 0 n 14

6 C + 1 1H B. 235 92 U + 1 0 n 87 35Br + 146 57 La + 31 0 n C. 226 88 Ra 222 86 Ra + 4 2He D. 2 1H + 2 1H 4 2He7. Which statement explains why nuclear waste materials may pose a problem?A. They frequently have short half-lives and remain radioactive for brief periods of time.B. They frequently have short half-lives and remain radioactive for extended periods of time.C. They frequently have long half-lives and remain radioactive for brief periods of time.D. They frequently have long half-lives and remain radioactive for an extended period of time