chem chap 11 nuclear chemistry

What is nuclear radiation?

It is capable of removing electrons from molecules to form ions in cells, hence the term ionizing radiation

What are free radicals?

Molecules that splinter into neutral fragments, and they can disrupt cellular processes

What does ionizing radiation affect?

The fastest growing cells and tissues such as white blood cells and bone marrow. It also disrupts DNA which causes mutation

What does 3/4ths of all exposure to radiation come from?

Background radiation, or natural sourced radiation

What causes most radiation?

Radon

What do we balance in nuclear reactions?

Nucleons (protons and neutrons)

What is conserved during a nuclear reaction?

Atomic number (bottom left) and mass number (top left)

What is a positron?

An electron with a positive charge but the same mass. ₊₁⁰e

At present levels of exposure, which form of radiation is most likely to give you cancer?

Medical x-rays

Which of the following isotopes is most likely to be a cause of natural radiation in our bodies?

⁴⁰K

What is alpha decay?

radon-222 atoms break down spontaneously, giving off alpha (a) particles. At. # decreases by 2

What is the formula for alpha decay?

^222₈₆Rn → ^4₂He + ^218₈₄Po

What is beta decay?

The heaviest isotope of hydrogen, hydrogen-3, often called tritium, decomposes. At. # increases by 1

What is the formula for beta decay?

^3₁H → ^0_-1e + ^3₂e

OR

^1₀n → ^1₁p + ^0_-1e

What happens in beta decay?

The atomic number increases by one, but the total number of nucleons remains the same

What is harder to stop as radiation goes from alpha to gamma?

Penetrating power, i.e. gamma rays are very durable

What is positron emission?

The change of a proton in the nucleus into a neutron and a positron, with the positron being emitted from the nucleus. At. # decreases by 1

What is gamma decay?

It has no charge and no mass. Neither the nucleon number nor the atomic number of the emitting atom is changed; the nucleus simply becomes less energetic.

What is the formula for positron emission?

^18₉F → ^0₊₁e + ^18₈O

What is electron capture?

a nucleus absorbs an electron from an inner electron shell, usually the first or second. When an electron from a higher shell drops to the level vacated by the captured electron, an X-ray is released. At. # decreases by 1

What is the formula for electron capture?

^1₁p + ^0_-1e → ^1₀n

OR

^125₅₃I + ^0_-1e → ^125₅₂Te

What are some differences between chemical equations and nuclear equations?

CHEM

-Atoms retain their identity

-Reactions usually only involve electrons

-Mass is conserved

NUC

-Atoms change their identity from one element to another

-Reactions involve mainly protons and neutrons

-Mass changes significantly

What is half-life?

The time required for ½ of the material to undergo radioactive decay

What has a mass of 1 and a charge of 0?

Neutron

What is the smallest particle between alpha, beta, neutron and proton?

Beta particle

For which type of radioactive decay is an electron found on the left side of the equation?

Electron capture

What is the equation for half-life?

Fraction remaining = 1/2ⁿ

What is carbon-14 dating?

The half-life of carbon-14 is 5730 years. Carbon-14 is formed in the upper atmosphere by the bombardment of ordinary nitrogen atoms by neutrons from cosmic rays

What is tritium dating?

Tritium is a radioactive isotope of hydrogen. It has a half-life of 12.26 years and can be used for dating objects up to 100 years old.

What is artificial transmutation?

Bombardment of stable nuclei with alpha particles, neutrons, or other subatomic particles can cause new elements to form.

What can tracers do?

• Detect leaks in underground pipes.

• Determine frictional wear in piston rings.

• Determine uptake of phosphorus and its distribution in plants.

What can radioisotopes do?

They can destroy microorganisms that cause food spoilage

What is radiation therapy?

Nuclear radiation can be used to kill cancerous cells. Radiation is most lethal to fastest growing cells. Radiation is aimed at the cancerous tissue. Patients undergoing radiation therapy often experience nausea and vomiting, which are early signs of radiation sickness.

What is gamma ray imaging?

Technetium-99m emits gamma radiation. It can be used to image the heart and other organs and tissues.

What is positron emission tomography (PET)?

A patient inhales or is injected with positron-emitting isotopes such as carbon-11 or oxygen-15. When positrons encounter electrons, they emit two gamma rays, which exit the body in opposite directions. PET scans can be used to image dynamic processes

Things that can stop radiation

Alpha: a sheet of paper

Beta: Sheet of aluminum foil

Gamma: lead

How do you protect yourself from radiation?

Distance and shielding (ex. lead bib at the dentist for protection from x-rays)

What is the mass-energy equation made by Einstein?

E=mc²

E= energy

m= mass

c= speed of light

What is binding energy?

When protons and neutrons combine to form a nucleus, a small amount of mass is converted into energy

What is nuclear fission?

It occurs when larger nuclei split into small nuclei.

What causes a chain reaction?

Fission of one nucleus produces neutrons that can cause the fission of other nuclei

What is the Manhattan project?

It consisted of four separate research teams attempting to:

• Sustain the nuclear fission reaction

• Enrich uranium

• Make fissionable plutonium-239

• Construct a fission atomic bomb

What is radioactive fallout?

Many radioactive isotopes are produced in a nuclear bomb blast. Some are particularly harmful to humans.

What is Strontium-90?

It can be ingested form contaminated dairy and vegetable products and accumulates in bone

What is Iodine-131?

Has a half-life of 8 days. It concentrates in the thyroid glands.

Power plants

Civilian nuclear power plants use uranium that is less enriched uranium-235

The nuclear chain reaction is controlled for the slow release of heat energy. The heat is used to make steam, which turns a turbine to produce electricity.

What is nuclear fusion?

a thermonuclear reaction in which smaller atomic nuclei are fused into larger nuclei. Fusion is the principal reaction in the sun. Much bigger than a fission reaction