The Nucleus : A Chemist’s View. Nuclear Symbols. Mass number, A (p + + n o ). Element symbol. Atomic number, Z (number of p + ). Balancing Nuclear Equations. A reactants = A products. 235 + 1 = 142 + 91 + 3(1). 92 + 0 = 56 + 36 + 3(0).
Mass number, A
(p+ + no)
Atomic number, Z
(number of p+)
Areactants = Aproducts
235 + 1 = 142 + 91 + 3(1)
92 + 0 = 56 + 36 + 3(0)
Zreactants = Zproducts
226 = 4 + ____
88 = 2 + ___
Atomic number 86 is radon, Rn
235 + 1 = 139 + 2(1) + ____
92 + 0 = 53 + 2(0) + ____
Atomic number 39 is yttrium, Y
Alpha production (a):
an alpha particle is a
Alpha decay is limited to heavy, radioactive
Limited to VERY large nucleii.
Beta production (b):
A beta particle is an
electron ejected from
Beta emission converts a neutron to a proton
Converts a neutron into a proton.
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
Opposite charges_________ each other.
Like charges_________ each other.
Positrons are the anti-particle of the electron
Positron emission converts a proton to a neutron
Electron capture: (inner-orbital electron is captured by the nucleus)
Electron capture converts a proton to a neutron
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
Decay occurs by first order kinetics (the rate of decay is proportional to the number of nuclides present)
N0 = number of nuclides
N = number of nuclides
remaining at time t
k = rate constant
t = elapsed time
t1/2 = Half-life (units dependent on rate constant, k)
Fusion:Combining two light nuclei to form a heavier, more stable nucleus.
Fission: Splitting a heavy nucleus into two nuclei with smaller mass numbers.
Nuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einstein’s equation:
DE = Dmc2
Dm = mass defect
DE = change in energy
c = speed of light
Because c2 is so large, even small amounts of mass are converted to enormous amount of energy.
A self-sustaining fission process is called a chain reaction.
Salt Bridge allows current to flow
1 M ZnSO4
1 M HCl
1 M HCl
a. cathode, oxidation
b. anode, reduction
c. anode, oxidation
d. cathode, reduction
Cd|Cd2+ || Cu2+|Cu
a. Cu2+ + Cd → Cu + Cd2+
b. Cu + Cd → Cu2+ + Cd2+
c. Cu2+ + Cd2+ → Cu + Cd
d. Cu + Cd 2+ → Cd + Cu2+
Iron Dissolves- Fe ® Fe+2
O2 + 2H2O +4e-® 4OH-
Salt speeds up process by increasing conductivity
Fe2+ + O2 + 2H2O ® Fe2O3 + 8 H+
1.0 M Cu+2
1.0 M Zn+2
1.0 M Cu+2
1.0 M Zn+2
Or the reverse if you want time to plate
Know the table
2. Recognized by change in oxidation state.
3. “Added acid”
4. Use the reduction potential table on the front cover.
5. Redox can replace. (single replacement)
I- + IO3- + H+ ® I2 + H2O
a) peroxides to oxides
b) Chlorates to chlorides
c) Electrolysis into elements.
d) carbonates to oxides
(f) The student adds 4 M ammonia to the copper sulfate solution, producing the complex ion Cu(NH3)+ (aq). The student remeasures the cell potential and discovers the voltage to be 0.88 volt. What is the Cu2+ (aq) concentration in the cell after the ammonia has been added?