Chemistry Do Now 3-13-19 Directions: Take out a sheet of notebook (Do Now sheet). Answer the following questions.   If a person is described as stable, what does that mean? If a person is described as unstable, what does that mean?

Chemistry Do Now 3-13-19 Key If a person is described as stable, what does that mean? The quality of maintaining a constant character in spite of forces that threaten to disturb it If a person is described as unstable, what does that mean? The quality of NOT being able to maintain a constant character when forces threaten to disturb it

Objective(s) Students will know how and why the atomic nucleus decays by taking notes, reading articles and completing a worksheet Mastery Level: 75% or better on the article questions and worksheet

Reminders This Friday, March 15, 2019 schools are closed for teacher professional development. Third quarter ends on April 3, 2019 so the window for posting 3rd quarter grades will be opening within the next 2 weeks.

Engage Do you agree or disagree with the statement, “People want to be stable.”? Why or why not?  What human actions make humans appear stable? Unstable?  Why do you think isotopes seek stability?

Explore Students will complete explore nuclear stability worksheet http://phet.colorado.edu/en/simulation/isotopes-and-atomic-mass .

Explain Students will read an article about radioactivity. Source: https://www.arpansa.gov.au/understanding-radiation/what-is-radiation/ionising-radiation/radioactivity What happens to nuclides that are unstable?

Explain – Copy these vocabulary words and their definitions radioactive decay: is the process by which an unstable atomic nucleus loses energy by emitting radiation, such as an alpha particle, beta particle, or a gamma ray ionizing ability: the ability of radioactivity to form ions depends on its mass. Ionizing ability is related to penetrating ability. Alpha particles are the most ionizing because they have the most mass. Gamma rays are the least ionizing because they have no mass

Penetrating Power of Radiation The penetrating power of alpha rays, beta rays, and gamma rays varies greatly. Alpha particles can be blocked by a few pieces of paper. Beta particles pass through paper but are stopped by aluminum foil. Gamma rays are the most difficult to stop and require concrete, lead, or other heavy shielding to block them.

Extend/Evaluate What happens to particles and energy during radioactive decay? Radiation Comparison: Using the handout Types of Radioactive Decay. Students first copy definitions of “radioactive decay,” “ionizing ability,” and “penetrating power.” Then, students complete a table of alpha, beta, and gamma decay which includes the particles released, relative energy released, and result of each type of decay. Students compare and contrast the properties of alpha, beta, and gamma decay by answering questions on the handout Types of Radioactive Decay.

Extend/Evaluate Students develop their own visual model of each type of radioactive decay (alpha, beta, gamma), focusing on the particles involved and the relative energies involved in each.