Chapter 9 - Nuclear Chemistry

Chemical reactions

outer electrons involved and elements keep their identity

Nuclear reaction

nuclei (& sometimes inner electrons) are involved and elements are transformed into new elements

Radioactivity

spontaneous change of an atomic nucleus

Becquerel (1896)

Discovered radiation - photographic plate exposed after he set a uranium rock on top of it

Radioactive isotopes are used

in medicine for diagnosis & treatment. Iodine isotopes used for diagnosing thyroid disease.

CH 2 (Refresher) Isotope

atoms with the same # of protons, but different number of neutrons (so different mass number = p+n)

When are Isotopes generally stable?

When the proton to neutron ratio is 1:1 for elements w/ atomic #20 or less

Beta Emission Particle

⁰_-1e

Beta Emission Reaction Product

new element with an atomic # one unit greater and the same mass #

Alpha Emission Particle

⁴₂He

Alpha Emission Reaction Product

new element with an atomic # two units lower and a mass # four units lower, than the original

Gamma Emission

Gamma rays are a high energy form if electromagnetic radiation (not particles)

Gamma ray

Y

Gamma Emission Reaction

Releasing Y does not change element, mass # or atomic #

Electromagnetic Radiation

consists of waves

Wavelength

distance between 2 wave crests

Electromagnetic Energy

The shorter the wavelength the higher the energy.

Half life t ½

Time it takes for ½ of a sample of radioactive material to decay

C-14 Dating

Use to determine age of archaeological objects

C-14 t ½ =

5730 years

Average Exposure to Radiation

359 mrem/year

100 rem

Radiation sickness

400 rem

50% of people die in 1 month

600 rem

lethal

Exposed to more naturally occurring radiation

Environment

Nuclear Fusion

(putting thins together) Two nuclei combine to produce a nucleus of heavier mass

Nuclear Fission (Atomic Energy)

(Breaking things apart) Large nuclei break into smaller nuclei after bombardment with neutrons producing atomic energy

Fission

Nuclear power plants & Nuclear bomb