nuclear decay. nuclear symbols element symbol mass number, a (p + + n o ) atomic number, z (number...
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Nuclear Decay
Nuclear Symbols
Element symbol
Mass number, A (p+ + no)
Atomic number, Z(number of p+)
U23592
Balancing Nuclear Equations
nKrBanU 10
9136
14256
10
23592 3
Areactants = Aproducts
Zreactants = Zproducts
235 + 1 = 142 + 91 + 3(1)
92 + 0 = 56 + 36 + 3(0)
Balancing Nuclear Equations #2
4222688Ra
226 = 4 + ____222
222
88 = 2 + ___86
86
Atomic number 86 is radon, Rn
Rn
Balancing Nuclear Equations #3
nInU 10
13953
10
23592 2
235 + 1 = 139 + 2(1) + ____95
3992 + 0 = 53 + 2(0) + ____
3995
Atomic number 39 is yttrium, Y
Y
Alpha Decay
Alpha production (a):
an alpha particle is a
helium nucleus ThHeU 23490
42
23892
Alpha decay is limited to heavy, radioactive
nuclei
ThU 23490
42
23892
242
242 orHe
Alpha Radiation
Limited to VERY large nucleii.
Beta Decay
Beta production (b):A beta particle is an electron ejected from the nucleus
ePaTh 01
23491
23490
Beta emission converts a neutron to a proton
0123491
23490 PaTh
0101 ore
Beta Radiatio
n
Converts a neutron into a proton.
Gamma Ray Production
Gamma ray production (g):
Gamma rays are high energy photons produced in association with other forms of decay.
Gamma rays are massless and do not, by themselves, change the nucleus
0023490
42
23892 2 ThHeU
Gamma Ray Production
Gamma ray production (g):
Gamma rays are high energy photons produced in association with other forms of decay.Gamma rays are massless and do not, by themselves, change the nucleus
0023490
42
23892 2 ThHeU
Positron Production
Positron emission:Positrons are the anti-particle of the electron
Positron emission converts a proton to a neutron
NeeNa 2210
01
2211
e01
Electron Capture
Electron capture: (inner-orbital electron is captured by the nucleus)
Electron capture converts a proton to a neutron
0020179
01
20180 AueHg
Types of Radiation
NuclearStability
Decay will occur in such a way as to return a nucleus to the band (line) of stability.The most stable nuclide is Iron-56
If Z > 83, the nuclide is radioactive
Graphic – Wikimedia user : Napy1kenobi
A Decay Series
A radioactive nucleus reaches a stable state by a series of steps
Graphic – Wikimedia Commons User Tosaka
Half-life
Graphic - http://cafreetextbooks.ck12.org/science/CK12_Earth_Science_rev.pdf
Decay Kinetics
Decay occurs by first order kinetics (the rate of decay is proportional to the number of nuclides present)
ktN
N
0
lnN = number of nuclides remaining at time t
N0 = number of nuclides present initially
k = rate constant
t = elapsed time
Calculating Half-life
kkt
693.0)2ln(2/1
t1/2 = Half-life (units dependent on rate constant, k)
Sample Half-Lives
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