Nuclear Decay

Nuclear Decay

What is Nuclear Decay?

Nuclear Decay

Radioactive elements change over time 

Alpha Decay: Lose an alpha particle 

Beta Decay: Lose a beta particle

What is a half life??

Half Life

This change is measured in half-lives 

Half life → The amount of time it takes (on average) for half of a sample of a radioactive element to decay into another element

Half life

Elements undergo exponential decay 

Half disappears in each time period

Elements

The half lives of different elements are different

What is carbon dating??

Calculating Half Life

We can find how much radioactive material is left after an amount of time

Or how much radioactive material was present at the beginning

What we need to know

Need to know 3 things 

1) How much was present at the beginning OR how much is left

2) How old the specimen is.

3) Half-life of the radioactive material

Equation

Present Amount = Past Amount / 2 ^ (Age / Half-Life)

Example

Find the how much Carbon-14 is present in a 28,500 year old human fossil. There was 1.5 grams of C-14 present when the specimen died. The half-life of C-14 is 5,700 years.

Example Data

Age of specimen: 30,000 years Half Life of C-14: 5,700 years Amount at the beginning: 1.5 g

Question: How much is still present?

Calculations