Nuclear Chemistry

Why do transmutations occur?

Because nucleus of the atom wants to become stable!!!

Beta Decay

Beta particles β: electrons ejected from the nucleus when neutrons decay ( n -> p+ +β- ) Beta particles have the same charge and mass as "normal" electrons.

What's a positron?

A positron is identical to an electron, except that it has a positive charge This is a particle with no mass yet positively charged.

Gamma Rays

Almost all nuclear decay also releases some energy in the form of gamma rays Gamma rays similar to X-Rays, but have more energy.

radioactive elements

The ratio in all nuclei of elements with atomic numbers greater than 83 makes them unstable. Most nuclei are stable The ratio of protons to neutrons determines the stability

half life

The time it takes for half of the atoms in a given sample of an element to decay

Nuclear Reactions and Energy

The total mass of a nucleus is less than the sum of the masses of the individual protons and neutrons. The matter that has been converted into energy is known as the mass defect. Turns out (in the unusual case of a nuclear reaction) mass can be converted to energy E = mc2

What stops gamma particles?

They have no mass. Gamma radiation has no charge. Most Penetrating, can be stopped by 1m thick concrete or a several cm thick sheet of lead.

radioisotope used in geological formations

U-238

C-14

Used in detecting the age of once living organisms (fossils)

I-131

Used in detecting thyroid cancer

U-238

Used in geological formation and age of rocks

Transmutation

When the nucleus of one element is changed into the nucleus of a different element.

When a nucleus decays, it emits radiation in the form of

alpha particles beta particles gamma particles

Which emission causes the atomic number of a nuclide to decrease by 2 and its mass number to decrease by 4?

an alpha particle

Which particle has the greatest mass

an alpha particle

Which particle has the least mass?

beta particle

What stops alpha particles?

can be stopped by a sheet of paper, clothing.

Which radioisotope is used to determine age of once living organisms?

carbon-14

Fission Reactions

high energy particle (usually a neutron) is captured by a nucleus, causing it to go unstable, and split. When the nucleus splits, a lot of energy is released. products are highly radioactive

chemical reactions

involve exchange or sharing of electrons

Nuclear chemistry

involves changes in the nucleus of an atom

An unstable nucleus spontaneously releases a positron. This is an example of

radioactive decay

environment radioactive risk factor

radioisotopes with long half lives

An unstable nucleus

spontaneously decays, forming products that are more stable.

spontaneous decay

the release of alpha, beta, positrons and/or gamma radiation from the nucleus of an unstable isotope

Artificial transmutation capture

when element is made radioactive by bombarding its nucleus with high energy particles.

main risk of radioactive powerplant

workers being exposed to radiation

What stops beta particles?

Can be stopped by aluminum foil or a block of wood.

Co-60

Cancer treatment, tracing

Radioisotope dangers

Damage to healthy tissue, Mutations - transferred to next generations Waste material with a long half life. Accidents.

Alpha decay

Emission of alpha particles a Helium nuclei two protons and two neutrons charge +2( quantity and quality?) can travel a few inches through air

Radioisotopes

For any element, an isotope that is unstable (and thus radioactive) is called a radioscope.

Gamma Decay

Gamma radiation γ : electromagnetic energy that is released. Gamma rays are electromagnetic waves.

Radioisotope Applications

Have applications in industry, medicine and research. Also source of energy with a little raw material.

Fusion Reactions

Involve the combining of light nuclei to form heavier ones. Require extremely high temperatures and pressures Major advantage - products are not highly radioactive

Balancing Nuclear equations

Label all components of the equation. You can use X for the unknown Balance charges ( bottom numbers) Balance mass ( top number ) Make sure that numbers left and right of an arrow are equal. Find a missing element.

when would it be a fission reaction?

The nuclear equation would be a fission reaction when there are larger compounds being the heavy nuclei are being converted into lighter nuclei.

the mass defect

The matter that has been converted into energy

Natural transmutation Decay

Radioactive element breaks down to simple more stable element

Nuclear decay

Radioactive isotopes changing their atomic structure.