Chapter 21 - Nuclear Chemistry Flashcards
Atomic number
Number of protons
Nucleons
Protons, neutrons, electrons
Nucleus is composed of the first two
Mass of atom
Number of protons and neutrons
Isotopes happen because
Varying neutrons
Radioactive
Unstable
Not uncommon for nuclides aka radionuclides
Alpha decay
Loss of an alpha particle (a helium nucleus)
Beta decay
Loss of the beta particle (a high energy electron)
Positron emission
Nuclei decay by emitting a positron a particle hay has the same mass as but and opposites charge to that of an electron
0
e
1
Gamma emission
The loss of a gamma ray which is high energy radiation that almost always accompanies the loss of a nuclear particle
0
0
Electron capture
Addition of an electron to a proton in the nucleus
Result is a neutron
Neutron-proton ratios
Any element with more than one proton will have repulsions between the protons in the nucleus
What helps keep the nucleus from flying apart?
A strong nuclear force
Neutrons key role
Stabilizing the nucleus
The ratio of neutrons to protons is an important factor
For smaller nuclei the neutron - proton ratio
Is close to 1:1 when z< 21
As nuclei get larger the number of neutrons needed to stabilize the nucleus
Increases
Belt of stability
Blue dark dots that show what nuclides would be stable
Above the belt of stability
Above the belt have too many neutrons (tend to be emitting beta particles)
Below the belt of stability
Nuclei have too many protons
Can become more stable by positron emission or electron capture
There are no stable nuclei with an atomic number greater than
83
These nuclei tend to decay by alpha emission
Large radioactive nuclei and stabilization
Cannot stabilize from one nuclear transformation
Undergo a series of decays often forming a nuclide of lead
Trends of number of protons and neutrons dealing with stability
Even is more stable than odds
How can one tap all the energy of a nucleus
Nuclear fission
Starts with the bombardment with a neutron which causes the decay and production of more neutrons (nuclear chain reaction)
Critical mass
Rate of neutron loss = rate of neutron creation by fission
Manhattan project
Development of the a bomb in WWII
Lead by Oppenheimer and groves
Used uranium 235
Curie/becquerel
Amt of radiation emitted by material
Rad/gray
Radiation dose absorbed by a person
Rem/sievert
Biological risk of exposure to radiation
Geiger counter
Used to measure the amount of activity present in radioactive sample
Detects current of ions
Kinetics of radioactive decay
Nuclear transmutation is a first order process
Kinetics of such a process obey this eqn: ln(Nt/N0) = -kt
Half life of radioactive decay
0.693/k
Radiocarbon dating
By comparing amount of a radioactive nuclide present at a given point in time with the amount normally present we can find the age of an object
Nuclear reactors
In nuclear reactors the heat generated by the reaction is used to produce steak that turns a turbine connected to a generator
Reaction is kept in check by control rods by blocking the paths of some neutrons
Nuclear accidents
Three mile island
Chernobyl
Fukushima
How can nuclear transformations be induced
By acceleration a particle and colliding it with the nuclide
Particle accelerator
Enormous
Circular tracks
Radii is miles long
Nuclear fusion
Superior method of generating power
Products not reactive
To achieve fusion the material must be state of plasma (super hot)
