1. Radiometric Dating
Half-life

2. Radioactivity
Radioactive Isotopes are unstable and emit/capture elemental particles, causing them to change over time.
Parent isotope – the original radioactive element
Daughter isotope – the decay product; what the parent changes into

3. Half Life
The time it takes for EXACTLY HALF of the unstable, parent isotope to decay.
This decay occurs at a CONSTANT RATE.
The half life is NOT affected by:
Time
Concentration of parent isotopes
Heat/pressure
Breakage/Crushing

4. Decay 100% parent 50 % parent 2 half lives 1 half life 50% daughter
25% original parent
6.25% parent
75% daughter
12.5% parent
4 half-lives
93.75%
daughter
87.5%
daughter
3 half-lives

5. Decay Table 1 2 3 4 Half Lives elapsed % parent remaining
% daughter created 1 2 3 4

6. Decay
100 %
75%
50%
% of Original Parent
25% 0%
HALF LIVES

7. Types of Decay Alpha Decay – an atom emits 2 protons and 2 neutrons
Atomic number and mass decrease

8. Types of Decay
Beta decay – a neutron breaks into a proton and an electron…the electron is emitted
atomic # ↑, atomic mass unchanged

9. Types of Decay
Electron capture – one electron is captured by the nucleus
Atomic number increases by 1