CHEM 1312 Chapter 20: Chapter 20
Chapter 20: Nuclear Chemistry
Nuclei and Nuclear Reactions.
• all atomic nuclei (except 1H) contain both protons and
neutrons
• nuclei of most atoms are stable (below atomic number 84)
-- atomic number 84 and above particles undergo
Radioactive decay – nuclear reaction involving
spontaneous emission of particles and/or
electromagnetic radiation by unstable nuclei
€
84
210 Po
→ Pb and α-particle
• radioactive isotope = atom that contains unstable nucleus
-- called radionuclides
-- undergo nuclear reactions (decreases E, more stable)
= emit high energy particles/electromagnetic radiation
• Nuclear transmutation =nuclear reaction that results from
the bombardment of nuclei by neutrons, protons, or other
nuclei
€
7
14 N
+ neutron →
€
6
14 C
+
€
1
1H
happens in atmosphere
neutrons from sun
• nuclear rxns very different from typical chemical rxns
• symbols for subatomic particles:
-- superscript = mass number (p + n)
-- subscript = atomic number (p)
--
€
–1
0e
in/from orbital;
€
–1
0
β
comes from nucleus
(neutron converted to proton and electron)
-- α particle identical to 4He nucleus
Balancing Nuclear Reactions:
• must balance the total of all atomic numbers and the total of
all mass numbers for the products and reactants
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
€
38
90Sr
is a β emitter:
€
38
90Sr
→
€
–1
0e
+
€
Z
mX
What is X?
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Identify X in the following nuclear equation:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
β
0
1
78
33 XAs −
+→
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Write balanced nuclear equations for the following:
Beta emission by magnesium-27
Formation of
€
22
48 Ti
through positron emission
Formation of 186Ir through electron capture
Alpha decay of
€
83
212 Bi
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -