Half Life & Radioactive Decay

What is half-life?

• a number that is always the same.

• 50% of the years it takes for something to decay 50%

• the number of years old a fossil might be.

• the time it takes for one half of the radioactive atoms in a sample to decay.

True/False: It does NOT matter how much of a substance there is; the half-life of that substance always remains the same.

• True

• False; does

• False; sometimes

The half-life of Carbon-14 is _____ years.

The substance we begin with in radioactive decay is the:

• parent material

• daughter product

• stable offspring

• nucleus

The substance we end with in radioactive decay is the:

• parent material

• daughter product

• stable offspring

• nucleus

Match the following parent isotopes to their daughter products.

**These are all ALPHA decay.

• Thorium-234

• Radium-223

• Radon-219

• Thorium-232

• Radon-228

• Americium-241

• Protactinium-237

• Uranium-238

Match the following parent isotopes to their daughter products.

**These are all BETA decay.

• Argon-40

• Technetium-99

• Nitrogen-14

• Potassium-40

• Ruthenium-99

• Rubidium-87

• Strontium-87

• Carbon-14

What radioactive substance is used for dating fossils that are 60,000 years old and younger?

• Polonium-214

• Phosphorus-32

• Carbon-14

• Potassium-40

• Uranium-238

What radioactive substance is used for dating fossils that are older than 60,000 years?

• Polonium-214

• Phosphorus-32

• Carbon-14

• Potassium-40

• Uranium-238

The half-life of Potassium-40 is _____ years.