Ch. 21 Nuclear Chemistry

Alpha decay

loss of an alpha-particle (helium nucleus)

^4₂He

Beta decay

loss of beta-particle (high energy e^-) from nucleus

⁰_-1e

positron emission

positron=particle w/same mass of e^- but opposite charge

⁰₁e

electron capture (k-capture)

adding an e^- to a proton in the nucleus

result": proton —> neutron

Gamma emission

loss of gamma ray — very high-energy electromagnetic radiation

smaller nuclei (Z<20) have a stable neutron to proton ratio of

1:1

it takes more neutrons to stabilize the nucleus as nuclei are larger…

above the belt…

nuclei have too many neutrons

tend to decay by emitting beta particles

it takes more neutrons to stabilize the nucleus as nuclei are larger…

below the belt…

have too many protons

tend to become more stable by positron emission or electron capture

There are no stable nuclei with an atomic number greater than…

83

nuclei with such large numbers tend to decay by alpha emission

Nuclei with an (even or odd) # of protons and neutrons tend to be more stable

even

Nuclei with 2, 8, 20, 28, 50, or 82 protons or 2, 8, 20, 28, 50, 82, or 126 neutrons tend to be (more/less) stable

more stable

all nuclear decay is a _____ order process

first order

binding energy (BE)

energy released when nucleons combine to form a nucleus

depends on mass defect

Mass defect (Δm)

difference between mass (in kg) of a stable nucleus and the individual nucleons that comprise it

E=(Δm)c²