How Can We Change How Can We Change Lead Into Gold?Lead Into Gold?

What Element is This?What Element is This?

The Four Universal ForcesThe Four Universal Forces

Gravitational forceGravitational force ElectromagnetismElectromagnetism WeakWeak StrongStrong

Who Discovered Who Discovered Radioactivity?Radioactivity?

In 1896, Henri Becquerel, along with Pierre In 1896, Henri Becquerel, along with Pierre and Marie Curie discovered radioactive and Marie Curie discovered radioactive waves by placing a rock containing waves by placing a rock containing Uranium on a photographic plate. They Uranium on a photographic plate. They shared the Nobel Prize in 1903.shared the Nobel Prize in 1903.

What is What is Radioactive Decay? Decay?

Radioactive decayRadioactive decay is is the set of various the set of various processes by which processes by which unstable unstable atomic nucleiatomic nuclei emit subatomic emit subatomic particles (radiation). particles (radiation).

Decay is said to occur Decay is said to occur in the in the parent nucleusparent nucleus and produces a and produces a daughter nucleusdaughter nucleus. .

Types of ParticlesTypes of ParticlesIdentity Symbol Charge Mass (amu)

Helium (Alpha)

4 α2

+2 4.001056

Electron (Beta)

0 β-1

-1 0.000549

Photon (gamma)

0 γ0

N/A N/A

Neutron 1 n0

0 1.008665

Proton 1 p1

+1 1.007276

Positron 0 β+1

+1 0.000549

What are their properties?What are their properties?Alpha: largest particle, can be stopped by paperBeta: can be stopped by a few layers of clothingGamma: most penetrating, stopped by lead

How To Solve Nuclear How To Solve Nuclear Decay Problems?Decay Problems?

How Can We Date Rocks?How Can We Date Rocks?

Half-life: The time it takes for half the element to decay

Half Life CalculationsHalf Life Calculations

• To calculate the ½ lifeTo calculate the ½ life

tt1/21/2 = = log 0.5___ log 0.5___ log(Nlog(Noo/N)/N)

NN = amount remaining = amount remainingNNo o = amount you started with = amount you started witht = time elapsedt = time elapsedtt1/2 1/2 = half life = half life

x t

Half - LifeHalf - Life The half life of I-123 is 13 hours. How The half life of I-123 is 13 hours. How

much of a 64 mg sample is left after 26 much of a 64 mg sample is left after 26 hours? hours?

NNoo = 64 mg = 64 mg t = 26 hourst = 26 hours tt1/2 1/2 = 13 hours = 13 hours

How many half lives have passed?How many half lives have passed? N = 64 x (0.5)N = 64 x (0.5)22

N = 16 mg remainingN = 16 mg remaining

Half - LifeHalf - Life

What is the difference What is the difference between Fission and Fusion?between Fission and Fusion?Fission: Splitting of atomic nucleus (nuclear power plant)Fusion: Fusing of atomic nuclei (sun)

Both release large amounts of energy

What Are The Uses of What Are The Uses of Radioactivity?Radioactivity?

There are many practical applications to the There are many practical applications to the use of radioactivity/radiation. use of radioactivity/radiation.

Radioactive sources are used to study living Radioactive sources are used to study living organismsorganisms

To diagnose and treat diseasesTo diagnose and treat diseases To sterilize medical instruments and foodTo sterilize medical instruments and food To produce energy for heat and electric To produce energy for heat and electric

powerpower To monitor various steps in all types of To monitor various steps in all types of

industrial processes.industrial processes. To determine age of fossilsTo determine age of fossils