Unit 2.8 Half Life

Why are radioactive isotopes with long half lives particularly harmful?

• They remain radioactive for much longer period of time

• They must be stored in a specific ways to avoid humans and the environment from being exposed to the radiation

State the 2 uses of nuclear radiation in the field of medicine

1. Examine internal organ

2. Controlling and destroying unwanted tissue

Describe the nature of radioactive decay

• Random

• Which nuclei decays and when it decay is random

• It is impossible to predict which nuclei will decay and when

Explain the basic idea being carbon dating

• All living things contain the same relative amount of carbon-12.

• When they die, the carbon decays at a known rate

• By measuring the amount of carbon remaining, the age can be calculated

Explain how a medical radioactive tracer is used

• The tracer is inserted in the body (often through bloodstream)

• The tracer is radioactive so decays

• A detector outside the body can detect this radiation and locate the tracer

What is the unit of radioactive activity

Bq

Define the activity of an unstable nucleus

Activity is the rate at which a source of unstable nuclei decays

What can be said about the half-life of a given radioactive isotope

It is constant

Define Half Life

The time it takes for the activity of a radioactive source to halve, or the time it takes for half the radioactive nuclei to decay.