Half Life Decay

Why is carbon-14 useful in dating archaeological artifacts?

• It has a very short half-life, making it precise for dating recent artifacts.

• It is found in atmospheric carbon dioxide and is absorbed by living organisms.

• It is the most stable isotope of carbon.

• It has a very long half-life, making it useful for dating ancient artifacts.

What is likely to happen to unstable nuclei with too many, or too few, neutrons?

• They will decay by emitting radiation.

• They will loose all their electrons.

• They will bond with other atoms.

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NGSS.HS-PS1-8

Radioactive materials have unstable...

• electrons

• protons

• nuclei

• neutrons

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NGSS.HS-PS1-8

What makes something radioactive?

• elements with an atomic number above 81

• an unstable nucleus

• contaminated sewage

• It decays over time

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NGSS.HS-PS1-8

The Radioactive decay is completely

• Spontaneous

• Programed

• Controlled

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NGSS.HS-PS1-8

The diagram shows 32 atoms

32 of the Red are the parent isotope

0 of the atoms are daughter isotopes

How many half-lives have occurred?

• 0

• 1

• 2

• 3

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NGSS.HS-PS1-8

The diagram shows 32 atoms.

16 of the Red are parent isotopes

16 of the Green are daughter isotopes

How many half-lives have occurred?

• 0

• 1

• 2

• 3

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NGSS.HS-PS1-8

Imagine you have 50,000 atoms of uranium-238. If U-238 has a half-life of 4.5 billion years, how many U-238 atoms will be left after 4.5 billion years?

• 25,000

• 50,000

• 12,500

• 0

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NGSS.HS-PS1-8

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years. 
How many grams are left after 1 half life? 

• 100 grams

• 25 grams

• 2 grams

• 50 grams

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NGSS.HS-PS1-8

Which diagram best represents the percentage of this radioactive isotope sample that will remain after 2 half-lives?

• 
• 
• 
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NGSS.HS-PS1-8