Unit 7: Changes in Matter
Name__________________________________
Chapter 22: Chemistry and the Environment
Section 22.1: Nuclear Reactions
Making Gold
 In the Middle Ages, individuals called alchemists spent a lot of time trying to make gold.
o To make an element from another element, you have to
perform a nuclear reaction
o There are two types of nuclear reactions, fission and
fusion
o Fission occurs when large (heavy) nuclei are split into
lighter ones
o Fusion occurs when small (light) nuclei combine to form
a heavier nucleus
o Recall the definition of isotope (atoms with a particular
mass number) and recall how to write isotope notation.
To Do: Show isotope notation for carbon-13.
How many protons?__________
How many neutrons?_________
Atomic number?_____________
Mass number?_______________
What is a nuclear reaction?
o Nuclear reactions involve either combining or splitting the nuclei of atoms
o Fission and fusion are nuclear reactions; they involve nucleons; accomplished in particle
accelerators
FISSION
Unit 7: Changes in Matter
Name__________________________________
Chapter 22: Chemistry and the Environment
To Do: Use in-text context clues or glossary to define the following.
nucleon—
Unit 7: Changes in Matter
Name__________________________________
Chapter 22: Chemistry and the Environment
o Chemical reactions involve electrons; accomplished in chemistry labs
Comparing Chemical and Nuclear Reactions
What part of atom?
How is it started?
What is the outcome?
How much energy?
How much energy?
Chemical Reactions
Outermost electrons
Atoms brought close together
Chemical bonds form
A small amount
Burning, eating, cleaning,
medicines
Nuclear Reactions
Protons and neutrons
Atoms smashed together
# of protons and neutrons change
A huge amount
The sun, nuclear power plants,
x-rays
Forces in the Nucleus
o Recall the strong nuclear force which holds nuclei together
o The strong nuclear forces causes every proton and neutron to be attracted to every other
proton and neutron; it is stronger than the electromagnetic force that causes the protons to
repel one another
o For heavier atoms, more neutrons than protons are needed to hold the nucleus together;
the neutrons add attractive force without increasing electromagnetic repulsion
What is Radioactivity?
o Radioactivity is any process where the nucleus emits particles and energy
To Do: Explain the difference between radioactive and radioactive decay. Define each in
your answer. Use the glossary or in-text context clues for help.
What is a radioactive isotope?
What is radiation?
o An unstable nucleus will do this until it transforms itself into a stable nucleus
o 3 common types of nuclear decay are alpha, beta, and gamma
 Alpha Decay-an alpha particle, a helium-4 nucleus is released from an unstable
nucleus. In alpha decay the number of protons and neutrons both decrease by 2.
Unit 7: Changes in Matter
Name__________________________________
Chapter 22: Chemistry and the Environment
 Beta Decay-a neutron splits into a proton and electron; the proton stays behind,
but the electron is emitted. In beta decay, the number of protons increases by one,
and the number of neutrons decreases by one.
 Gamma Radiation-the release of high energy, electromagnetic radiation. When
gamma radiation is emitted, the numbers of protons and neutrons do not change.
To Do:How is an alpha particle depicted?__________________or______________________
How is a beta particle depicted?____________________or______________________
How is a gamma particle depicted?______________________________
To Do: Explain the difference between stable and unstable. Define each in your answer.
Use the glossary or in-text context clues for help.
Using nuclear reactions for our energy needs
o The sun is a multi-step fusion reaction
o Nuclear reactors in nuclear power plants use fission
Unit 7: Changes in Matter
Name__________________________________
Chapter 22: Chemistry and the Environment
o Nuclear reactions often involve nuclear waste
o Half-life is the length of time it takes for half of the radioactive material to decay to
another form
o Decay products can also be radioactive, so waste products need to be stored for long
periods of time (Yucca Mountain)
o U.S. gets about 20% of its energy from nuclear power plants
o Fusion to produce energy is being researched
Other Uses of Nuclear Reactions
o Radioactive isotopes can be used to detect problems in organ systems.
o The age of some fossils can be determined using radioisotopes such as carbon-14.
o It is possible to figure out the age of objects made from plants or animals that are
between 50,000 and a few thousand years old using carbon dating.
o Medical tracers, food irradiation, weapons detection, radioactive dating all involve using
a detecting nuclear reactions
Section 22.2: Carbon Reactions in the Environment
We all depend on the carbon reactions performed by plants
o Plants convert the sun’s energy into products we use.
o Basic Photosynthesis Reaction: Plants use chlorophyll to absorb energy from the sun to
convert carbon dioxide and water to glucose and oxygen. Plants use the glucose for
energy and release the oxygen back to the environment.
o We then make use of the energy and oxygen by-products of photosynthesis.
Unit 7: Changes in Matter
Name__________________________________
Chapter 22: Chemistry and the Environment
We depend on carbon reactions for transportation.
o Cars burn fossil fuels for energy.
o Use of (the burning of) fossil fuels affects the environment by releasing greenhouse gases
into the atmosphere. Increased levels of greenhouses gases (or global warming gases)
have far-reaching detrimental effects on our environment. Greenhouse or global
warming gases include CO2 (carbon dioxide), CH4 (methane), and N2O (nitrous oxide).
To Do: A fossil fuel is defined as an organic substance found underground in deposits
formed in a previous geologic period and used as a source of energy. Name as many fossil
fuels as you can.
Are fossil fuels considered to be a renewable energy resource?
The Combustion Reaction in Cars
o Incomplete combustion of fuel leads to air pollutants being released into our atmosphere.
o In addition to CO2, CO (carbon monoxide) is produced, which is poisonous
o Nitrous oxides are also produced which lead to acid rain formation.
o Ozone and hydrocarbons are also released, which are both harmful to humans.
o The catalytic converter, introduced in the 1970’s, reduces hydrocarbon and carbon
monoxide emissions by converting these molecules to carbon dioxide and water.
Unit 7: Changes in Matter
Name__________________________________
Chapter 22: Chemistry and the Environment