chapter 10 nuclear chemistry when controlled, nuclear energy has many practical uses… this...
TRANSCRIPT
CHAPTER 10
Nuclear Chemistry
When controlled, nuclear energy has many practical uses…
This submarine is powered by a fission reaction that releases large amounts
of energy
10.1 Radioactivity
• Key Concepts– What happens during nuclear decay?
– What are three types of nuclear radiation?
– How does nuclear radiation affect atoms?
– What devices can detect nuclear radiation?
When Henri ____________ placed uranium salts on a photographic plate and then developed the plate, he found a __________ image.
The image was caused by __________ that had not been observed before.
He shared the 1903 Nobel Prize for Physics with Marie and Pierre ___________.
Becquerel
foggy
rays
Curie
Radioactivity is the process in which an ______________ atomic nucleus emits charged particles and energy.
Any atom containing an unstable nucleus is called a radioactive isotope, or _________________ for short.
Nuclear Decay
During nuclear decay, atoms of one element can change into atoms of a ______________ element altogether.
different
unstable
radioisotope
Scientists can detect a radioactive substance by measuring the nuclear radiation it gives off.
Nuclear radiation is charged _______________ and _________________ that are emitted from the nuclei of radioisotopes.
What does the word emitted mean?
Types of Nuclear Radiation
particles
energy
given off / released
Types of Nuclear Radiation
Alpha Decay
An alpha particle is a ________________ charged particle made up of two protons and two neutrons—the same as a ____________ nucleus.
When a uranium-238 sample decays, it emits alpha particles.
• An alpha particle has a 2+ charge• An alpha particle has a mass of 4 amu.• The symbol for an alpha particle, ______, shows its
mass and charge.
Types of Nuclear Radiation
positively
helium
He42
The nuclear equation for the alpha decay of uranium-238 is shown below.
• The mass number on the left (238) ____________ the sum of the mass numbers on the right (____________).
• The atomic number on the left (92) equals the sum of the atomic numbers on the right (___________).
• The equation is ________________.
Types of Nuclear Radiation
equals
=
238
92
balanced
A beta particle is an ______________ emitted by an unstable nucleus.
– The symbol for a beta particle is _______.
During beta decay, a neutron decomposes into a proton and an electron. The proton stays trapped in the nucleus, while the electron is released.
A beta particle is assigned an atomic # of ______. A beta particle is assigned a mass number of ____.
Types of Nuclear Radiation
electron
e 0-1
-1
0
The balanced equation for beta decay of thorium-234 is shown below.
Types of Nuclear Radiation
=
Gamma Decay
A gamma ray is a penetrating ray of __________ emitted by an unstable nucleus.
Gamma radiation has ____ mass and ____charge.
Like X-rays and visible light, gamma rays are energy waves that travel through __________ at the speed of light.
Types of Nuclear Radiation
energy
no no
space
Gamma radiation also involves balanced equations, but the energy of the nucleus __________________.
Types of Nuclear Radiation
decreases
energyemitted
The penetrating power of nuclear radiation varies with the type.
Types of Nuclear Radiation
Balancing Nuclear Equations
Write a balanced nuclear equation for the alpha decay of polonium-210.
Types of Nuclear Radiation
206
82
Look up atomic # on P.T.
Pb=
Write a balanced nuclear equation for the beta decay of carbon-14.
14
7
Look up atomic # on P.T.
=N
Background radiation is nuclear radiation that occurs _______________ in the environment.
• Radioisotopes in air, water, rocks, plants, and animals all contribute to background radiation.
• Cosmic rays are streams of charged particles (mainly protons and alpha particles) from outer space.
• Background radiation levels are generally ________ enough to be safe.
Effects of Nuclear Radiation
naturally
low
When nuclear radiation exceeds background levels, it can ____________ the cells and tissues of your body.
• Nuclear radiation can ______________ atoms.
• It may break the bonds in your _________, affecting cell functions.
Effects of Nuclear Radiation
damage
ionize
DNA
__________ gas is produced underground as the uranium in rocks and soil decays.
Effects of Nuclear Radiation
Insulation, modern windows, and modern building materials keep radon from escaping.
Radon gas dissolved in water is released through agitation.
Radon naturally diffuses up through the ground.
Radon is produced by the nuclear decay of uranium found in rocks and soil.
Radon enters through pinholes and cracks in the foundation.
Radon
Causes lung cancer
A ______________ counter uses a gas-filled tube to measure ionizing radiation.
• When nuclear radiation enters the tube, it ionizes the atoms of the gas.
• The ions produce an electric
______________, which can be
measured.
Many people who work with or
near radioactive materials wear
_______________ to monitor
their exposure to nuclear radiation.
Detecting Nuclear RadiationGeiger
current
film badges
Assessment Questions
1. What happens when an atomic nucleus decays? a. The atom loses an electron and gains energy.
b. Some of the protons in the nucleus are converted to neutrons.
c. A nucleus breaks into two parts of approximately equal mass.
d. An unstable nucleus emits charged particles and energy.
Assessment Questions
2. During alpha decay, the nucleus emits an alpha particle, ora. proton.b. neutron.c. deuterium nucleus.d. helium nucleus.
Assessment Questions
3. Which isotope balances the nuclear equation for the alpha decay of thorium-232?
a.
b.
c.
d.
Assessment Questions
4. Nuclear radiation can damage cells in the body by a. ionizing atoms in molecules in the cell.
b. making holes in the cell wall.
c. making isotopes in the cell radioactive.
d. causing water to vaporize and rupture the cell.
Assessment Questions
5. A Geiger counter measures radiation by detecting ions formed when charged particles pass through a tube filled with gas.
TrueFalse