1. 2.2 Quick Review
What is the atomic number and mass number for the element shown below?
Is this a neutral atom or an ion? How do you know?
Atomic number = 6
Mass number = 12
Neutral…same # of p+ and e-

2. Review Questions
What type of macromolecule is being put together in the picture below?
protein

3. 2-3 What Happens When Matter Undergoes Change?
Concept 2-3 Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

4. Matter Undergoes Physical, Chemical, and Nuclear Changes
Physical change
No change in chemical ___________________
Ex: Ice cap ____________ back into liquid water
Chemical change, chemical reaction
Change in chemical composition
________________ and ___________________
Ex: coal (C) oxygen gas (O2)  carbon dioxide (CO2)
Nuclear change
Natural radioactive decay through ________________ isotopes
Nuclear fission – when nuclei ___________
Nuclear fusion – when nuclei ______________
composition
melts
products
reactants
unstable
split
combine

5. Beta particle (electron)
Radioactive decay
Alpha particle
(helium-4 nucleus)
Radioactive isotope
Gamma rays
Figure 2.9: There are three types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Beta particle (electron)
Radioactive decay occurs when nuclei of unstable isotopes spontaneously emit fast-moving chunks of matter (alpha particles or beta particles), high-energy radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of the three items shown in the diagram.
Fig. 2-9a, p. 43

6. Nuclear fission Uranium-235 Energy Fission fragment n n Neutron n n
Figure 2.9: There are three types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Radioactive isotope Radioactive decay occurs when nuclei of unstable isotopes
spontaneously emit fast-moving chunks of matter (alpha particles or beta particles), high-energy radiation (gamma rays), or both at a fixed rate. A particular radioactive isotope may emit any one or a combination of the three items shown in the diagram.
Fig. 2-9b, p. 43

7. Nuclear fusion occurs when two isotopes of light elements, such
Reaction
conditions
Fuel
Products
Proton
Neutron
Helium-4 nucleus
Hydrogen-2
(deuterium nucleus)
100
million °C
Energy
Figure 2.9: There are three types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Hydrogen-3
(tritium nucleus)
Neutron
Nuclear fusion occurs when two isotopes of light elements, such
as hydrogen, are forced together at extremely high temperatures
until they fuse to form a heavier nucleus and release a tremendous
amount of energy.
Fig. 2-9c, p. 43

8. We Cannot Create or Destroy Matter
Law of conservation of matter
Whenever matter undergoes a physical or chemical change, no atoms are created or destroyed
The atoms are simply __________________
According to this law, can we really ever just throw something away?
rearranged
No…it may sit in a landfill
or be recycled

9. 2-4 What is Energy and What Happens When It Undergoes Change?
Concept 2-4A When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics).
Concept 2-4B Whenever energy is changed from one form to another in a physical or chemical change, we end up with lower-quality or less usable energy than we started with (second law of thermodynamics).

10. Energy Comes in Many Forms (1)
work
Energy is the capacity to do ____________ or transfer __________
Work is done any time an object is ________ a certain distance
Work = force x distance
Example: picking up your textbook
Heat transfer example: heat flowing from your
stove to your finger
heat
moved

11. Energy Comes in Many Forms
Two Main Types of Energy
1. Kinetic energy - ______________ energy
Flowing water
Wind
Heat – the total kinetic energy of
all moving _________________
Electromagnetic radiation –
energy travels in the form of a
____________
motion
particles
waves

12. The Electromagnetic Spectrum
There are many different forms of electromagnetic radiation…each have a different ______________ and ____________________
wavelength
energy content
Figure 2.11: The electromagnetic spectrum consists of a range of electromagnetic waves, which differ in wavelength (the distance between successive peaks or troughs) and energy content.
Fig. 2-11, p. 45

13. Potential Energy
2. Potential Energy - ____________ and potentially available for use Examples: Water stored behind a dam Chemical energy stored in the carbon atoms of coal
stored
Figure 2.12: The water stored in this reservoir behind a dam in the U.S. state of Tennessee has potential energy, which becomes kinetic energy when the water flows through channels built into the dam where it spins a turbine and produces electricity—another form of kinetic energy.
Fig. 2-12, p. 45

14. We change potential energy to kinetic energy Examples
Holding your book and ______________ it
gasoline  kinetic energy that ________ a car  heat transferred to environment
Water behind a dam  flowing water  spinning turbine  ___________________
dropping
propels
electricity

15. Nuclear Energy to Electromagnetic Radiation
Nuclear energy from _________ that occurs in the sun converts to electromagnetic _______________
fusion
radiation
Figure 2.13: Energy from the sun supports life and human economies. This energy is produced far away from the earth by nuclear fusion (Figure 2-9, bottom). In this process, nuclei of light elements such as hydrogen are forced together at extremely high temperatures until they fuse to form a heavier nucleus. This results in the release of a massive amount of energy that is radiated out through space.
Fig. 2-13, p. 46

16. Energy Comes in Many Forms
Sun provides _______ of earth’s energy
Warms earth to comfortable temperature
Provides plants with the energy for photosynthesis  provides all other organisms with ___________
All of this energy is provided at ____ cost to us…keeping with our solar energy principle of ___________________
99%
food no
sustainability

17. Energy Comes in Many Forms
The sun’s direct input of solar energy also produces several indirect forms of _____________ solar energy
Wind
Hydropower – falling or flowing __________
Biomass – all of the energy stored in in the chemical bonds within ____________
renewable
water
plants

18. Commercial energy sold in the market place make the remaining ______ of the energy we use
Main source – burning ______, ________, and natural _______
These fuels are called __________________ because they were formed over millions of years from the decaying remains of ancient plants and animals (aka fossils) 1%
oil
coal
gas
fossil fuels

19. Fossil fuels
Figure 2.14: Fossil fuels: Oil, coal, and natural gas (left, center, and right, respectively) supply most of the commercial energy that we use to supplement energy from the sun. Burning fossil fuels provides us with many benefits such as heat, electricity, air conditioning, manufacturing, and mobility. But when we burn these fuels, we automatically add carbon dioxide and various other pollutants to the atmosphere.
Fig. 2-14a, p. 46

20. Some Types of Energy Are More Useful Than Others
High-quality energy
_______________...so it has a high capacity to do work
High-temperature heat
Strong winds
Fossil fuels
Low-quality energy
______________....so low capacity to do work
Low energy heat created by moving molecules in the atmosphere or ocean
Concentrated
Dispersed

21. Ocean Heat Is Low-Quality Energy
Figure 2.15: A huge amount of the sun’s energy is stored as heat in the world’s oceans. But the temperature of this widely dispersed energy is so low that we cannot use it to heat matter to a high temperature. Thus, the ocean’s stored heat is low-quality energy. Question: Why is direct solar energy a higher-quality form of energy than the ocean’s heat is?
Fig. 2-15, p. 47

22. Energy Changes Are Governed by Two Scientific Laws
Thermodynamics – the study of energy ________________
Energy transfers are governed by two Main Laws
transformations
First Law of Thermodynamics
(Law of conservation of energy)
Energy is neither ______________ nor ______________ in physical and chemical changes…it can only be __________________
created
destroyed
transferred

23. When your car’s tank runs out of gasoline, what are you actually losing?
Second Law of Thermodynamics
Energy always goes from a ___________ useful to a less ______________ form when it changes from one form to another
Example: Resulting low quality energy often takes the form of __________ that flows into the environment…random motion of air or water molecules further _______________ this heat
High quality energy
more
useful
heat
dispersed

24. This is why we need to use technologies that conserve energy….
We can recycle ______________ and reuse it, but not high-quality energy
This is why we need to use technologies that conserve energy….
Some bad examples…
Incandescent light bulbs and internal combustion engines
matter

25. Energy-Wasting Technologies
Both technologies waste
high-quality energy through
poor ___________ and large
heat transfers
design
87% of h.q.e. converted
to heat
Figure 2.16: Two widely used technologies waste enormous amounts of energy. In an incandescent lightbulb (right), about 95% of the electrical energy flowing into it becomes heat; just 5% becomes light. By comparison, in a compact fluorescent bulb (left) with the same brightness, about 20% of the energy input becomes light. In the internal combustion engine (right photo) found in most motor vehicles, about 87% of the chemical energy provided in its gasoline fuel flows into the environment as low-quality heat. (Data from U.S. Department of Energy and Amory Lovins; see his Guest Essay at CengageNOW.)
80% of h.q.e.
converted
to heat
(fluorescent)
95% of h.q.e.
converted
to heat
(incandescent)
Fig. 2-16a, p. 48

26. Review Questions
What is the difference between physical, chemical, and nuclear changes?
What do we call the study of energy transformations?
No composition
change
Unstable isotope
causes change
in nucleus
composition
change…new
product
thermodynamics

27. Which picture below represents low quality energy
Which picture below represents low quality energy? And high quality energy?
high
low
Fossil fuel
Ocean heat