Chapter 20 --> Radioactivity and Nuclear Chemistry

Describe Alpha rays.

Have a charge of 2+ and a mass of 4 amu; needs to be helium

Describe beta rays.

Have a charge of -1 and no mass; electron like

describe gamma rays.

form of light energy; not a particle

what is a positron?

positively charged electron; emitted by unstable nuclei

what is electron capture?

a low energy electron is pulled into the nucleus of unstable nuclei

what is a nuclide?

the nucleus when discussing nuclear properties

what is a nuclear equation?

atomic numbers and mass numbers are conserved; the sum of the mass and atomic numbers must be equal on both sides

Describe gamma emission.

no loss of particles from the nucleus, no change in composition of the nucleus, same atomic and mass number, least ionizing but most penetrating , occurs after some other type of decay

what is strong force?

particles in the nucleus are held together by a very strong attractive force found only in the nucleus; acts over short distances

what is a nucleon?

protons and neutrons

what do the neutrons do?

stabilize the nucleus, since they add to the strong force but don't repel each other like protons do

What are the kinetics of radioactive decay equations the same as?

half-life

the shorter the half-life, we say the sample is _____________

hotter

Describe radiocarbon dating.

all things that are or were once alive contain carbon.

which type of carbon is radioactive?

C-14

what is C-14's half life?

5730 years

What keeps C-14 producing at nearly the same rate it decays?

atmospheric chemistry

Radiocarbon dating can only measure ______________ objects.

young

what is nuclear fission?

a large nucleus splits into two smaller nuclei via reaction with neutron

what is fusion?

small nuclei can be accelerated to smash together to make a larger nucleus

both fission and fusion ________________________

release enormous amounts of energy

to produce fissionable uranium, the natural uranium must be _______________ in 235U.

enriched

what is a nuclear reactor core?

control rods with neutron-absorbing material which allows the rate of neutron flow through the reactor to be controlled, the control robs control the rate of nuclear fission

describe a nuclear plant.

used 50kg of fuel to generate enough electricity for 1 million people; no air pollution

describe coal burning.

uses about 2 million kg of fuel to generate enough electricity for 1 million people, produces NO2 and SOx with add to acid rain, produces CO2 which adds to green house effect

what are some problems with nuclear power?

core meltdown water loss, waste disposal; highly radioactive, reprocessing

where does energy from fission come from?

some of the mass of the nucleus is converted into energy

what is mass defect?

the difference in mass between the separate nucleons and the combined nucleus

what is binding energy?

energy that is released when the nucleus forms

the _____________ the binding energy per nucleon, the __________ stable the nucleus

greater; more

what are the effects of radiation on life?

radiation ionizes important molecules in living cells

what are the 3 types of radiation effects?

acute radiation damage, increased cancer risk, genetic effects

what unit is the amount of danger to humans measured in?

rem

list some nonmedical uses of radioactive isotopes.

smoke detectors, insect control, food preservation, radioactive tracers, chemical analysis