Warm Up 10-5-151. Ra-225 half-life is 15 days, how many

grams are left after 45 days if you started with 90g?

2. How can a unstable isotope (radioactive) become normal?

3. Can radiation be good?

Agenda-Go over quiz-Notes Unit 3-5-Finish WS Nuclear decay

HomeworkOct 9 - Test Unit 3Oct 9 - Midterm Exam (45 Qs)Oct 9 - Online HW Unit 3

Quiz Unit 3• Version 1

1.v.e. = 5, total e = 15

2.N, Ge, In, Hg

3.Alkaline earth metals

4.Si and B

• Version 2

1.v.e. = 2, total e = 38

2.F, S, P, Ga

3.Noble gases

4.I and F

5. False, moving across the period also add more electrons to the atom but radius decreases

6. Atomic mass and properties

Unit 3-5

Characteristics of Nuclear Decay

Characteristics of Some Radiation

Alpha- weakest, a thin barrier can stop (they are big and heavy and can’t travel very far)Beta- clothing, wood, or aluminum can stop this radiation.

Gamma- highly energized can be stop by concrete or lead

Alpha Decay

Problem: the nucleus has too many protons which cause excessive repulsion. Solution: In an attempt to reduce the repulsion, a Helium nucleus is emitted.

Alpha emission (decay)

4 2 He

238 92 U

Identify the product formed when uranium-238 alpha decays

4 2 He + 234

90 Th

Determines which atom from the periodic table

Beta Decay

Problem: too many neutrons not enough protons.

Solution: a neutron is turned into a proton and one electron is then ejected.

beta emission (decay) 0-1 e

14 6 C

Identify the product formed when carbon-14 emits beta particle

0 -1 e + 14

7 N

Gamma Decay

Problem: the nucleus is at too high an energy.

Solution: The nucleus falls down to a lower energy state and, in the process, emits a high energy photon known as a gamma ray.

gamma emission (decay)

00 γ

14 6 C

Identify the product formed when carbon-14 releases gamma rays

0 0 γ + 14

6 C

Explaining mass defect:

E=mc2 says that mass can be converted into

energy when the nucleus is formed

Nuclear Fusion

- When multiple nuclei smash into each other forming a larger nucleus.

- How our sun produces energy and how hydrogen bombs work

Nuclear Fusion Equations

• Nuclear fusion involves the joining together of nuclei.

Nuclear Fission- A large nucleus is split into

two or more smaller nuclei (process sped up by hitting it with a neutron)

- Releases Alpha, Beta, Gamma Rays and a lot of energy- Used to power nuclear weapons (atomic bombs), nuclear subs, & nuclear power plants

Nuclear Fission• Nuclear fission involves a nucleus

breaking up into smaller nuclei.

“Fat Man”

“Little Boy”

Nuclear Fission

Nuclear Fission• Chernobyl power plant - 1986

Nuclear Fission• Fukushima - 2011

Assignments

• Notes Summary

• Finish the Nuclear Decay worksheet (due today)

Students’ Work Ethics Affected by Peers

1. What was the main points of this news?

2. What was most important in this piece of information?

3. How can this news be related or impact people lives or solve problems/improve society?

4. What is your opinion on what you heard?

• Alpha radiation: consists of He nucleus– 238

92 U 42 He + 234

90 Th

• Beta radiation: electrons formed by the decomposition of a neutron– 14

6 C 0-1 e + 14

7 N

• Gamma radiation: high energy electromagnetic radiation; often emitted with alpha or beta radiation

Summary of Radiation

Summary of Radiation

Property Alpha radiation

Beta radiation

Gamma radiation

Composition

Alpha particle (He nucleus)

Beta particle (electron)

High energy EM radiation

Symbol , 42 He , 0

-1 e

Penetrating power

low moderate Very high

Shielding Paper, clothing

Metal foil Lead, concrete