Sc Standards PS 2.2 Illustrate the fact that the atoms of elements exist as stable or unstable isotopes.

Universal Forces Gravitational Force- Gravitational Force- Force of attraction between two masses. Force of attraction between two masses. Electro-magnetic Force- Electro-magnetic Force- Force of attraction between two opposite charges (force of repulsion between two like charges). Force of attraction between two opposite charges (force of repulsion between two like charges). Weak Nuclear Force- Weak Nuclear Force- A force found within the nucleus which is responsible for certain types of nuclear decay. A force found within the nucleus which is responsible for certain types of nuclear decay. Strong Nuclear Force- Strong Nuclear Force- A force found within the nucleus which helps hold the nucleus together. (The glue that keeps the protons and neutrons close together.) A force found within the nucleus which helps hold the nucleus together. (The glue that keeps the protons and neutrons close together.)

Nuclear Energy It’s All About the NUCLEUS! It’s All About the NUCLEUS!

Radiation Think back to the egg lab. What would happen if there were too many protons and neutrons to fit in the egg? Think back to the egg lab. What would happen if there were too many protons and neutrons to fit in the egg?

Radiation Particles and Energy emitted from the breakdown of the nucleus of an atom. Particles and Energy emitted from the breakdown of the nucleus of an atom.

History Lesson Henri Becquerel ( ) Henri Becquerel ( ) Father of Radioactivity Father of Radioactivity Discovered nuclear radiation in Discovered nuclear radiation in Shared his findings with Marie and Pierre Currie in Paris, France. Shared his findings with Marie and Pierre Currie in Paris, France.

Marie and Pierre Curie Marie and Pierre Curie Discovered the radioactive elements Radium and Polonium. Discovered the radioactive elements Radium and Polonium.

Radioactive Elements Look at the periodic table Look at the periodic table Which elements do you think have too many protons and neutrons to fit in their nucleus without leaking out? Which elements do you think have too many protons and neutrons to fit in their nucleus without leaking out? Are there any other elements that might have radioactive ISOTOPES? Are there any other elements that might have radioactive ISOTOPES?

How does radiation occur? Atoms are radioactive only if there is not enough strong force (binding energy) to hold the nucleus together.

Decay When particles leak out and the number of protons change……the atom changes into a different element.

When will my nucleus overflow? For ‘smaller’ elements the nucleus is stable when the neutron to proton ratio is 1:1. (In other words, for every one neutron there is one proton.) When this balance is upset, too many neutrons, the nucleus will become unstable and it overflows... decays. For ‘smaller’ elements the nucleus is stable when the neutron to proton ratio is 1:1. (In other words, for every one neutron there is one proton.) When this balance is upset, too many neutrons, the nucleus will become unstable and it overflows... decays. For ‘larger’ elements the ratio is stable at 3:2; and unstable when too many or too few neutrons are present. For ‘larger’ elements the ratio is stable at 3:2; and unstable when too many or too few neutrons are present.

3 Types of Radiation 1. Alpha particles 2. Beta particles 3. Gamma Rays

Alpha Particles Made of 2 protons and 2 neutrons Made of 2 protons and 2 neutrons +2 charge +2 charge Like a Helium nucleus Like a Helium nucleus Slow moving Slow moving Stopped by paper Stopped by paper

Beta Particles High speed electron High speed electron Charge of –1 Charge of –1 No mass No mass Stopped by plastic or Stopped by plastic or wood wood Formed when a neutron breaks down into a new proton and new electron Formed when a neutron breaks down into a new proton and new electron

Gamma Rays Most penetrating form of radiation Most penetrating form of radiation Pure energy Pure energy Can damage human tissues Can damage human tissues Stopped by lead or concrete Stopped by lead or concrete

Uses of Radiation Smoke alarms contain a weak source made of Americium-241. Alpha particles are emitted from here. In nuclear medicine, Beta particles are used in PET scans to image the brain to detect abnormalities. Gamma radiation is also used to sterilize hospital equipment, especially plastic syringes that would be damaged if heated. They are also used in treatment of cancerous tumors.

Fun Science Word of the Day Transmutation An atom of one element changing (mutating) into another element during radioactive decay.

Nuclear Decay Nuclear Decay Alpha Emission Alpha Emission parent nuclide daughter nuclide alpha particle Numbers must balance!!

Wrapping It Up Practice transmutation as you follow the 4.6 million year journey of uranium-235 to lead-207 Practice transmutation as you follow the 4.6 million year journey of uranium-235 to lead-207