Learning Goal Write a balanced nuclear equation showing mass numbers and atomic numbers for radioactive decay Balancing Nuclear Equations In a process called radioactive decay the nucleus breaks down by emitting radiation ID: 918858
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Slide1
5.2 Nuclear Reactions
In the nuclear equation for alpha decay, the mass number of the new nucleus decreases by 4 and its atomic number decreases by 2.
Learning Goal Write a balanced nuclear equation showing mass numbers and atomic numbers for radioactive decay.
Slide2Balancing Nuclear Equations
In a process called radioactive decay, the nucleus breaks down by emitting radiation.
The process is represented by a nuclear in whichthe mass number and atomic number may change.the sum of the mass numbers and the sum of the atomic numbers are equal for the reactants and the products: Mass number sum: 251 = 251 251Cf 247Cm + 4He 98 96 2
Atomic number sum: 98 = 98
Core Chemistry Skill
Writing Nuclear Equations
Slide3Alpha Decay
Alpha decay occurs when a radioactive nucleus emits an alpha particle
, forming a new nucleus with a mass number that is decreased by 4 and an atomic number that is decreased by 2.
Slide4Guide to Completing Nuclear Equations
Slide5Equation for Alpha Emission
Complete the following nuclear equation for the decay of
americium-241:STEP 1 Write the incomplete nuclear equation.
ANALYZE Given
Need
THE PROBLEM
Am-241, balanced nuclear equation
alpha decay
4
2
He
Slide6Equation for Alpha Emission
Complete the following nuclear equation for the decay of
americium-241:STEP 2 Determine the missing mass number. 241 = ? + 4 241 − 4 = ? 241 – 4 = 237 (mass number of new nucleus)
STEP 3
Determine the missing atomic number.
95
= ? + 2 95 – 2 = ? 95 − 2 = 93 (atomic number of new nucleus)4
2
He
Slide7Equation for Alpha Emission
Complete the following nuclear equation for the decay ofamericium-241:
STEP 4 Determine the symbol of the new nucleus. The element that has atomic number 93 is neptunium, Np. STEP 5 Complete the nuclear equation. 42
He
Slide8Beta Decay
In the nuclear equation for beta decay, a beta particle, an electron, is emitted from the nucleus when a neutron in the nucleus breaks down, forming a proton and a beta particle and increasing the atomic number by 1.
0–1e
Slide9Equation for Beta Decay
Write an equation for the decay of 42
K, a beta emitter.STEP 1 Write the incomplete nuclear equation.
0
–1
e
Slide10Equation for Beta Decay
Write an equation for the decay of
42K, a beta emitter.STEP 2 Determine the missing mass number. 42 = ? + 0 42 – 0 = ? 42 − 0 = 42 (mass number of new nucleus)STEP 3
Determine the missing atomic number.
19
= ? − 1 19 + 1 = ? 19 + 1 = 20 (atomic number of new nucleus) 0–1
e
Slide11Equation for Beta Decay
Write an equation for the decay of
42K, a beta emitter.STEP 4 Determine the symbol of the new nucleus. The element that has atomic number 20 is calcium (Ca). STEP 5 Complete the nuclear equation.
0
–1
e
Slide12Study Check
Write the nuclear equation for the beta decay of
60Co.
Slide13Solution
Write the nuclear equation for the beta decay of 60Co.
STEP 1 Write the incomplete nuclear equation.
Slide14Solution
Write the nuclear equation for the beta decay of 60
Co.STEP 2 Determine the missing mass number. 60 = ? + 0 60 – 0 = ? 60 − 0 = 60 (mass number of new nucleus)STEP 3 Determine the missing atomic number. 27
= ? − 1
27 + 1 = ?
27 + 1 = 28 (atomic number of new nucleus)
Slide15Solution
Write the nuclear equation for the beta decay of 60
Co.STEP 4 Determine the symbol of the new nucleus. The element that has atomic number 28 is nickel (Ni). STEP 5 Complete the nuclear equation.
Slide16Positron Emission
In positron emission,
a proton is converted to a neutron and a positron.the mass number of the new nucleus is the same, but the atomic number decreases by 1. 0+1e
Slide17Gamma Radiation
In gamma radiation
,energy is emitted from an unstable nucleus, indicated by m following the mass number.the mass number and the atomic number of the new nucleus are the same.00γ
Slide18Summary of Types of Radiation
When the nuclei of alpha, beta, positron, and gamma
emitters emit radiation, new and more stable nuclei are produced.
Slide19Producing Radioactive Isotopes
Radioactive isotopes are produced
when a stable nucleus is converted to a radioactive nucleus by bombarding it with a small particle.in a process called transmutation.
When nonradioactive B-10 is bombarded by an alpha particle, the products are radioactive N-13 and a neutron.
Slide20Equation for Producing New Isotopes by Bombardment
Write the balanced nuclear equation for the bombardment of nickel-58 by a proton, , which produces a radioactive isotope and an alpha particle.
STEP 1 Write the incomplete nuclear equation.
Slide21Equation for Producing New Isotopes by Bombardment
Write the balanced nuclear equation for the bombardment of nickel-58 by a proton,
, which produces a radioactive isotope and an alpha particle.STEP 2 Determine the missing mass number. 1 + 58 = ? + 4 59 – 4 = ? 59 − 4 = 55 (mass number of new nucleus)STEP 3 Determine the missing atomic number.
1 + 28 = ? + 2
29 − 2 = ?
29 − 2 = 27 (atomic number of new nucleus
)
Slide22Equation for Producing New Isotopes by Bombardment
Write the balanced nuclear equation for the bombardment of nickel-58 by a proton,
, which produces a radioactive isotope and an alpha particle.STEP 4 Determine the symbol of the new nucleus. The element that has atomic number 27 is cobalt (Co). STEP 5 Complete the nuclear equation.
Slide23Study Check
What radioactive isotope is produced when a neutron bombards
98Tc, releasing an alpha particle?
Slide24Solution
What radioactive isotope is produced when a neutron bombards 98
Tc, releasing an alpha particle?STEP 1 Write the incomplete nuclear equation.
ANALYZE Given Need
THE PROBLEM
neutron bombardment balanced nuclear
Tc-98
equation
Slide25Solution
What radioactive isotope is produced when a neutron bombards
98Tc, releasing an alpha particle?STEP 2 Determine the missing mass number. 1 + 98 = ? + 4 99 – 4 = ? 99
− 4 = 95 (mass number of new nucleus)
STEP
3
Determine the missing atomic number. 43 + 0 = ? + 2 43 − 2 = ? 43 − 2 = 41 (atomic number of new nucleus)
Slide26Solution
What radioactive isotope is produced when a neutron bombards
98Tc, releasing an alpha particle?STEP 4 Determine the symbol of the new nucleus. The element that has atomic number 41 is niobium (Nb).
STEP
5
Complete the nuclear equation
.