Nuclear Chemistry

(1845-1923) discovered X-rays, a high energy form of light (1895)

(1852-1909) found that uranium ores emit radiation that can pass through objects (like x-rays) and affect photographic plates (1896)

(1867-1934) Marie and Pierre worked with Becquerel to understand radioactivity. Shared a Nobel prize in physics in 1903. She later won a nobel prize in chemistry in 1911/

Invented the cyclotron which was used at UC Berkeley to make many of the transuranium elements

The spontaneous breakdown of atomic nuclei, accompanied by the release of some form of radiation (also called radioactive decay)

Time required for half of a radioactive sole to decay

One element being converted into another by a nuclear change

Isotopes of elements that are identified by the number of their protons and neutrons

The sequence of Nuclides that an element changed into until It forms a stable nucleus

Using half life information to determine the age of objects. C-14/C-12 is common for organic artifacts. Uranium is common for rocks

Large nucleus breaking down into pieces of about the same mass

Two or more light nuclei blend to form one or more larger nuclei

Alpha particles, beta particles, gamma rays

Same as a helium nucleus, 4/2 He, w a mass of 4 amu. Travels about 1/10th speed of light, most easily stopped of the particles, least dangerous

High speed electrons, 0/-1e, with a mass of 0.00055 amu and travel at nearly the speed of light, they can be stopped by a sheet of aluminum, more penetrating/dangerous than alpha

Extremely high energy light, y, with no mass, and are the most penetrating (several cm’s of lead are needed to stop them) they can cause severe damage

Emission of positron from nucleus 0/+1e

Inner electrons captured by nucleus 0/+1e, caused when electron becomes proton, outer electron fills vacancy…giving off energy

Total time, starting amount, half life, ending amount

Time it takes for the amount of substance or the activity of the substance to drop to half is the same WHEREVER you start on the graph. This is a first-order reaction. Half lives can range

Alpha 4/2He, Beta 0/-1e, positron 0/+1e, neutron 1/0n

The particle is on the right side of the equation

The nucleus has too many protons compared to neutrons (positron decay)
The nucleus has too many neutrons compared to protons (beta decay)
The nucleus is too big (alpha decay)

N:p Ratio between 1 and 1.5

You can calculate the time needed to change from what is expected to what is actually found

Many substances can be radioactive and then followed as they move through the body

Current nuclear reactors use fission reactions to produce heat which is used to turn water into steam and drive turbine engines that produce electricity

Powered by nuclear fusion…this is related to the fact that the most abundant element in the universe is hydrogen…followed by helium

Means element can be split when bombarded by neutrons

Each spitting nucleus can emit neutrons that can split other nuclei is the basis

Use different isotoprs

Involves several steps – 4(1/1H)–> 4/2He+2 0/1e+energy

Use isotopes of hydrogen (deuterium and tritium)

equation Basis for explaining where energy associated with nuclear changes comes from

When a nuclear change occurred, the mass of the products is slightly less than the mass of the reactants. The loss in mass is called the mass defect

e= the energy
m=the mass defect
c= the speed of light, 3.000 c 10^8 m/s

Equivalent to burning 3 billion kg of coal

1 neutron changes into 1 proton + 1 negative beta particle (the atomic # increases by one due to the new proton. The mass # is unchanged… A neutron is gone. To maintain electrical neutrality, a negative beta particle is also formed

1 proton changes into 1 neutron+1 positron particle (the atomic # decreases by one due to the loss of a proton. Since it changed into a neutron the mass # is unchanged)

Often unstable after decay, many decays may occur before stable nucleus is formed

Method used to verify the identity of newly formed atoms

Daughter products can be even more radioactive than parent so disposal/storage is a problem

Ionize the air as they pass through by striking atoms and knocking off electrons

Detects and measures radiation by: radioactive particles pass through chamber with two electrodes, ionized particles migrate to + and – electrodes and complete the circuit

Use tiny piece of radioactive Am to keep circuit flowing due to ionized particles. Smoke particles attract ionized particles, break the circuit, and set off alarm

Kept ionized by tiny bits of radioactive material to more easily attract tiny bits of dust

At UC Berjeley were able to use E.O. Lawrence’s cyclotron to make larger atoms (elements 93 and 94)

Uranium Z=92

Medical field, further understanding of nucleus

As of July 2000, 118

Force of attraction that holds nucleus together

Energy produced when atoms nucleons are bound together, energy released when a nucleus is formed from nucleons

Stable isotopes fall into a narrow band

If you replace one atom with radioisotope- monitor radioactive emissions

Damage DNA of cancer cells

Delivered by machine

Substance introduced to body

Light, microwaves