At the bell

Filling out your planner and sitting quietly

Split a blank piece of paper with a partner

Or come grab scrap paper off my desk

Vocabulary Review

Unconformity-

Law of Superposition-

Absolute age dating-

Absolute Age Dating

Absolute Age Dating

the process of establishing the age of an object by determining the number of years it

has existed

Scientists have figured out an exact or precise age

We are absolutely sure of the age

Chemistry Review

● What parts make up an atom?

What does it mean to be radioactive?

Radioactivity- the spontaneous decay of certain unstable atomic nuclei

But what does that mean?

Radioactive Isotope● Means we have an element with a

changed mass● It has more neutrons!

Radiocarbon dating

When an organism dies, the amount of carbon-14 it contains gradually decreases as it decays.

By comparing the ratio of carbon-14 to carbon-12 in a sample, radiocarbon dates can be determined.

All elements have radioactive isotopes

Some just don't have any stable forms like

● Uranium● Radon● Radium● Plutonium

Parent Material

● Is the radioactive isotope you start with

Like Uranium

Half Life

A half-life is the amount of time necessary for one-half of the nuclei in a sample (parent) to decay to a stable isotope (daughter).

Daughter Material

● Is whatever element the radioactive isotope decays to

After one half-life

Only half the parent material remains

So after 2 half lives…..how much remains?

Which is less stable

The parent isotope or the daughter product?

Cobalt-60

The half-life of cobalt-60 is 5 years.

If you have 10 grams of Co-60,

how much do you have after 15 years?