# Presentation: 816941

## NUCLEAR CHEMISTRY

*	**	**Nuclear Particles:*
*	**	**	**       *_*Mass*__*	*_* *_*Charge*_*	*_*Symbol*_
*PROTON **	**      1 amu**	**    +1**	**        H+,   H,   p*
*NEUTRON  **	**      1 amu**	**    0**	**	**   n*

- © Copyright 1994-2002 R.J. Rusay

## Number of Stable Nuclides 

***Elements 48 through 54***

-                                             **Atomic                        Number of**
**Element                              Number (*****Z*****)                 Nuclides**

**Cd   **                                     **48                                    8**
- In                                          49                                    2
**Sn                                         50                                   10**
- Sb                                         51                                     2
**Te                                         52                                     8**
- I                                            53                                     1
**Xe                                        54                                      9**

***Magic numbers are 2, 8, 20, 28, 50, or 82 protons or neutrons.***
***Even numbers of protons and neutrons are more stable than odd.***

## Distribution of Stable Nuclides

*	**Protons    Neutrons     Stable Nuclides      %*
*Even           Even              157                58.8*
*Even           Odd                 53                 19.9*
*Odd           Even                 50                 18.7*
*Odd            Odd                   7                   2.6*

- 267

- 100.0%

- Total =

## Nuclear Decay / Radioactivity

*Unstable nuclei “decay” i.e. they lose particles which lead  to other elements and isotopes.*
*The elements and isotopes produced may also be unstable and go through further decay.*
*	**	**	**	**	**	*

- © Copyright 1994-2002 R.J. Rusay

*Nuclear decay reactions conserve mass & energy.*

## Nuclear Particlesemitted from unstable nucleii

*Emitted Particles:*
*   **	**                    **Mass   Charge  Symbol*
*alpha particle   **4 amu      +2           *
*beta particle**	** **very small       **-1*
*gamma        **very very small   **0*
*positron         **very small**    **+1*

- © Copyright 1994-2002 R.J. Rusay

## Nuclear Penetrating Power

- © Copyright 1994-2002 R.J. Rusay

*alpha particle:  low*
*beta particle: moderate*
*gamma: high*
*X-rays? *

***Water***

## Exposure to Radiation

## NUCLEAR STABILITYPatterns of Radioactive Decay

*Alpha decay ****(**********–**heavy isotopes*
*Beta decay ****(********************** –**neutron rich isotopes*
*Positron emission ****(******************)****–**proton rich isotopes*
*Electron capture–**proton rich isotopes**  *
*X-rays:*
*Gamma-ray emission (**********most all unstable isotopes*
*Spontaneous fission–**very heavy isotopes*

## 	Alpha Decay–Heavy Elements

*238**U** **  ****   **234**Th +  **** + e*
*	**        *t*1/2 **= 4.48 x 10** 9 **years*
*210**Po  ****    **206**Pb  +  **** + e*
* **	**         *t*1/2 **= 138 days*
*256**Rf  ****   **252**No  +  **** + e*
*	**        *t*1/2 **= 7 ms*

***For Cobalt 60 predict  the alpha decay product:***

## Beta Decay–Electron Emission

*   **n        ****        p**+** +  ****** +  Energy*
* **14**C       ****        **14**N +  ******  +  Energy*
*	**           *t*1/2**= 5730 years*
*90**Sr       ****        **90**Y +  ******  **+  Energy*
*    **	**    *t*1/2**= 30 years*
*247**Am    ****        **247**Cm +  ****** +  Energy*
*	**            *t*1/2**= 22 min*
*131**I        ****         **131**Xe +  ******  +  Energy*
*  **	**          *t*1/2** = 8 days*

## Electron Capture–Positron Emission

**p****+  ****+ e****-**** **** n + Energy  ****= Electron capture**

**p****+**** **** n + e****+**** + Energy  ****= Positron emission**

- 51Cr  +  e-  51V  +  Energy
-           *t*1/2 = 28 days

- 7Be  7Li  +    +  Energy
-          *t*1/2 = 53 days

**?**** ** +  e-  177Ir  +  Energy

- 144Gd  **?**  +   +  Energy

## Nuclear Decay

*Predict the Particle or element:*
*Thallium 206 decays to Lead 206.**	**	**	**What particle is emitted?**	**	**	**	**	**	**	**	**	**	**	*
*Cesium 137 goes through Beta decay. **	**	**What element is produced and what is its mass?**	**	**	**	**	**	**	**	**	*
*Thorium 230 decays to Radium 226.**	**	**	**What particle is emitted?*

- © Copyright 1994-2002 R.J. Rusay

## Nuclear Decay Series

*Nuclear Decay Series*

*If the nuclei produced from radioactive decay are unstable, they continue to decay until a stable isotope results.*
*An example is Radium which produces Lead*

- © Copyright 1994-2002 R.J. Rusay

## The 238U Decay

***The ******238******U Decay***
***Series***

## Nuclear Decay Measurement

*Nuclear Decay Measurement*

*Decay can be measured with an instrument that detects “disintegrations”. The rate can be obtained by “counting” them over  a period of time. **	**e.g. disintegrations / second (dps)*
*The rate of decay follows first order kinetics*
*The  rate law produces the following equation for the *_*half life: *_

- © Copyright 1994-2002 R.J. Rusay

## Nuclear Reactions

*The mass of the visible universe is 73% H**2 **   and 25% He. The remaining 2%, “heavy” elements, have atomic masses >4.*
*The “heavy” elements are formed at very high temperatures (T>10**6  o**C) by *_*FUSION*_*, i.e. nuclei combining to form new elements.*
*There is an upper limit to the production of heavy nuclei at A=92, Uranium.*
* **Heavy nuclei split to lighter ones by *_*FISSION*_

- © Copyright 1994-2002 R.J. Rusay

## Slide 17

## NUCLEAR ENERGY

*EINSTEIN’S EQUATION FOR THE CONVERSION OF MASS INTO ENERGY *
*E = mc**2*
*      *m* = mass (kg)*
*      *c* = Speed of light *
- 		c* = 2.998 x 10**8** m/s*

## Mass   Energy

**	****   *****Electron volt (ev)****  *
*               **The energy an electron acquires when it moves through  *
*                **a potential difference of one volt:*
***                                    ******1 ev = 1.602 x 10******-19******J***
*                **Binding energies are commonly expressed in units*
*                **of megaelectron volts (Mev)*
***                                    ******1 Mev = 10******6****** ev = 1.602 x 10****** -13******J***
*                **A particularly useful factor converts a given mass defect*
*                **in atomic mass units to its energy equivalent in electron*
*                **volts: *
*	**	**	****1 amu = 931.5 x 10******6****** ev = 931.5 Mev***

## Binding Energy per Nucleon of Deuterium

- Deuterium has a mass of 2.01410178 amu.

- Hydrogen atom = 1 x 1.007825 amu = 1.007825 amu
-           Neutrons = 1 x 1.008665 amu = 1.008665 amu
-                                                               2.016490 amu

-              Mass difference = theoretical mass - actual mass
-                   = 2.016490 amu - 2.01410178 amu = **0.002388 amu**

- Calculating the binding energy per nucleon:
- Binding energy         -0.002388 amu x 931.5 Mev/amu
-      Nucleon                               2 nucleons
-                               =** -1.1123 Mev/nucleon**

- =

## Nuclear Reactions

*Fission and Fusion reactions  are highly exothermic (1 Mev /  nucleon).*
*This is 10 **6** times larger than “chemical” reactions which are about 1 ev / atom.*
* **Nuclear fission was first used in a chain reaction:*

- © Copyright 1994-2002 R.J. Rusay

## Nuclear Reactions:_________________________

*Fission and Fusion reactions  are highly exothermic (1 Mev /  nucleon).*
*This is 10 **6** times larger than “chemical” reactions which are about 1 ev / atom.*

*Fission:** *

*Fusion: *

## Nuclear Reactions

* **Nuclear fission was first used in a chain reaction:*

## Slide 24

## Slide 25

## Nuclear Reactions / Fission

*The Fission Chain Reaction proceeds geometrically:  1 neutron **** 3 **** 9 **** **27 **** 81 etc.*
* **1 Mole of U-235 (about 1/2 lb) produces **	**	**2 x 10**10** kJ which is equivalent to the combustion of *_***800 tons***__* *_*of Coal!*
*Commercial nuclear reactors use fission to produce electricity....Fission [“atomic”] bombs were used in the destruction of Hiroshima and Nagasaki, Japan, in August 1945.*

- © Copyright R.J.Rusay 1994-2002

## The Nuclear Dawn

***The Nuclear Dawn***
***August 6, 1945***

## Nuclear Power Plant

## Worldwide Nuclear Power Plants

## Chernobyl, Ukraine

***Chernobyl, Ukraine***
*April,1986 and April,2001*

## Nuclear Reactions / Fusion

*Fusion has been described as the chemistry of the sun and stars.*
*It too has been used in weapons. It has not yet found a peaceful commercial application*

- © Copyright 1994-2002 R.J. Rusay

*The application has great promise in producing relatively “clean” abundant energy through the combination of Hydrogen isotopes particularly from **2**H, deuterium and  **3**H, tritium: (NIF/National Ignition Facility, LLNL)*

## National Ignition FacilityLawrence Livermore National Laboratory

## National Ignition FacilityLawrence Livermore National Laboratory

- © Copyright 1994-2002 R.J. Rusay

## Hydrogen Burning in Stars and

***           ******Fusion Reactions***

- 1H  + 1H    2H  +   + 1.4 Mev
- 1H  +  2H  3He  +  5.5 Mev
- 2H  +  2H  3He   + 1n   +  3.3 Mev
- 2H  +  2H  3H   +  1H   +  4.0 mev
- 2H  +  3H  4He  +  1n   +  17.6 Mev              Easiest!
- 2H  +  3He  4He  +  1H  +  18.3 Mev

## Helium “Burning” Reactions in Stars

- 12C  +  4He  16O
- 16O  +  4He  20Ne
- 20Ne  + 4He  24Mg
- 24Mg  +  4He  28Si
- 28Si  +  4He  32S
- 32S  +  4He  36Ar
- 36Ar  +  4He  40Ca