Ch 20 - Nuclear Chemistry

nuclear reactions

• involve protons and neutrons

• atomic numbers change

• different isotopes of an element behave different

• small amount of matter converted to energy

isotopes

• elements that have the same number of protons, but different numbers of neutrons

• same atomic number (Z), different mass numbers (A)

• refers to the entire atom (including electrons)

nuclide

refers specifically to the nucleus of the isotope

alpha

• A = 4

• Z = 2

• Charge = 2+

• identity = Helium (nucleus)

beta

• A = 0

• Z = -1

• Charge = -1

• identity = electron

positron

• A = 0

• Z = 1

• Charge = +1

• identity = positron (electron with a positive charge or antimatter)

gama

• A = 0

• Z = 0

• Charge = 0

• identity = high energy photon

neutron

• A = 1

• Z = 0

• Charge = 0

• identity = neutron

How to write nuclear equations

parent nuclide → daughter nuclide + particle (ray/radiation)

How must a nuclear equation be balanced?

atomic mass (superscripts) and nuclear charge (subscript) must be equal on both sides

alpha decay

• the nucleus ejects an alpha particle

• mass number decrease by 4

• atomic number decrease by 2

beta decay

• a neutron becomes a proton by ejecting a beta particle (or electron)

• mass number stays the same

• atomic number increases by 1

What is a the most radioactive decay process?

the release of a gamma particle

The release of a gamma particle

• there is no charge in atomic or mass number

• the daughter isotope is simply a lower energy form of the parent

position emission

• a type of beta decay that releases a position equivalent of an electron

• mass number stays the same

• atomic number decreases by one

tracers

• radioactive atoms used to determine what ordinary atoms are doing

• can be easily traced because they give off decay

In atoms with a lower atomic mass…

• the most stable nuclei tend to have the same number of protons and neutrons

In atoms with higher atomic masses…

• the atomic mass because more than double the atomic number

What elements has the highest atomic number that has a stable isotope?

lead

Why do nuclides decay?

to bring daughter isotope closer to the belt of stability than the parent isotope

half life

the time it takes for a sample of an isotope to get to half its original number of atoms