UNIT 3 - Nuclear Chemistry Flashcards
what does the stability of an atomic nucleus depend on?
the proton:neutron ratio
what is the required neutron:proton ratio for smaller elements?
1:1
what is the required neutron:proton ratio for larger (and heavier) elements?
15:1
what is radioactivity?
the result of unstable nuclei rearranging to form stable nuclei with emission of energy
what is radiation connected with?
radiation is connected solely with the nucleus
what is radiation independent of?
physical state of the element and is not affected when the element forms compounds
what is alpha radiation (α)?
slow moving positively charged particles attracted to the negative plate
what is beta radiation (β)?
fast moving negatively charged particles attracted to the positive plate
what is gamma radiation (γ)?
electromagnetic radiation travelling at the speed of light with no deflection
what is the nature of alpha radiation?
helium nucleus
what is the nature of beta radiation?
electron
what is the nature of gamma radiation?
EMR
what is the nature of radiation?
what its similar to
what is the symbol for alpha radiation?
⁴₂He
what is the symbol for beta radiation?
0
-1e
what is the symbol for gamma radiation?
doesnt have one
what is the charge on alpha radiation?
2+
what is the charge on beta radiation?
1-
what is the charge on gamma radiation?
doesnt have one
what is the mass of an alpha radiation particle?
4 amu
what is the mass of a beta radiation particle?
1/2000 amu
what is the mass of a gamma radiation particle?
none
what happens when a radioactive isotope decays by alpha emission?
the nucleus loses 2 protons and two neutrons
what is transmutation?
when the number of protons changes, causing the element to change
what happens if a nucleus has too many neutrons?
a neutron will be converted into a proton and an electron
how is beta radiation emitted?
the proton stays inside the nucleus and the electron is ejected from the nucleus as beta radiation
what does gamma radiation occur with?
other types of radiation
what is gamma radiation a mechanism for?
releasing energy
what does gamma radiation not affect?
the atomic or mass number
what is the disintegration of a nucleus?
an entirely random event and it is impossible to predict when a particular atom will decay
in what situations is radioactive decay predictable?
when the atom is unstable
what is half-life?
the time taken for half of the nuclei of a particular isotope to decay
what is half life abbreviated to?
t 1/2
what is the half life of any isotope independant of?
the mass, temperature, pressure, concentration, catalysts, or state of the sample
how are radioisotopes used in medicine?
they are used for radioactive labelling in the diagnosis and treatment of disease
how are radioisotopes used in industry?
241Am is used in domestic smoke alarms
how are radioisotopes used in scientific research?
32P and 14C can be used to determine the uptake of phosphates and carbon dioxide in plants, this technique is called ISOTOPIC LABELLING
how is 14C formed?
14C is a radioactive isotope formed in the upper atmosphere by the bombardment of nitrogen by neutrons
why is there a constant level of 14C in the atmosphere?
because the rate of formation is equal to the rate of decay
what do all living plants and animals contain?
14C
what happens when a plant or animal dies?
it no longer absorbs 14C so the level of radioactivity will decrease
how can the age of a sample be calculated?
by using half life and comparing the activity with that of current 14C levels
