Do now!Can you

continue the questions you

started last lesson?

Today’s lesson

• Use the term half-life in simple calculations, including the use of information in tables or decay curves.

• Give and explain examples of practical applications of isotopes.

Do now!

Tomekitis

½ - life

• This is the time it takes half the nuclei to decay

half-life (t½)

Number of nuclei undecayed

timeA graph of the count rate against time will be the same shape

Different ½ - lives

• Different isotopes have different half-lives

• The ½-life could be a few milliseconds or 5000 million years!

half-life (t½)

Number of nuclei undecayed

time

Examples

• A sample of a radioactive isotope of half life 2 hours has a count rate of 30 000 counts per second. What will the3 count rate be after 8 hours?

Examples

Uses of radioactive isotopes

Used as Tracers

Used as Tracers

Used as Tracers

Killing microbes

Killing microbes

Thickness control

Thickness control

Smoke detection

Checking welds

Carbon dating

Summary sheet

“Can you………?”

Test!

• Wednesday 16th March (11X)

• Monday 21st March (11A)

Can you answer the questions on pages 261 and

265?