1. Comet Tempel 1 as seen last week by the Stardust-NeXT spacecraft.
This is the second visit to this comet. The first involved the “Deep Impact” mission.

2. A Universe of Matter and Energy
What is matter?
What is energy?

3. Matter – material such as rocks, water, air; “stuff” composed of atoms
Energy – makes or has the potential to make matter move!
The history of the universe, including biological organisms, is based upon the interplay between matter and energy.

4. Three Basic Types of Energy
kinetic
energy of motion
potential
stored energy; e.g., chemical, gravitational, electrical, etc.
radiative
energy transported by light (electromagetic radiation)

5. Conservation of Energy
Fundamental law of nature
Energy can be neither created nor destroyed
It can change form or be exchanged between objects.
The total energy content of the Universe was determined in the Big Bang and remains the same today.
K.E.
P.E.
R.E.

6. (m is mass, v is velocity)
energy of motion
K.E. = 1/2 mv2
(m is mass, v is velocity)
Kinetic Energy (K.E.):

7. temperature On the microscopic level: is a measure of the
average kinetic energy
of particles within a substance

8. Temperature Scales

9. Temperature vs. Heat Temperature is the average kinetic energy.
Heat (thermal energy) is the total kinetic energy.
lower T
higher T
less heat
more heat
same T

10. Sound waves are a form of kinetic energy on a microscopic level (organized vibration of molecules)

11. Potential Energy: Energy that is “stored” within an object and that has the potential of being released in a different form

12. Gravitational Potential Energy
gravitational potential energy is the energy which an object stores due to its ability to fall
It depends on:
the object’s mass (m)
the strength of gravity (g)
the distance which it can fall (d) g m d
P.E. = mgd

13. gravitational potential energy
P.E. = mgd

14. Mass-Energy Potential Energy
mass-energy: energy is stored in matter itself
this mass-energy is what would be released if an amount of mass, m, were converted into energy
E = mc2
[ c = 3 x 108 m/s
is the speed of light]

15. Chemical Potential Energy
Chemical potential energy: energy stored chemical bounds

16. There are many additional examples of potential energy. e. g
There are many additional examples of potential energy. e.g., stretched springs, …

17. Energy, while conserved, can be transformed from one type of energy to another
Potential Kinetic

18. Potential Kinetic

19. Kinetic Potential

20. Orbits & Energy Uphill Maximum Potential Energy Maximum Kinetic Energy
Downhill

21. Radiative energy: energy carried by electromagnetic radiation (light).

22. Light Light as a wave Light as a particle (photon)
A vibration in an electromagnetic field
through which energy is transported.
Light as a wave
Light as a particle
(photon)

23. Properties of Waves WAVELENGTH (: Distance between adjacent crests
FREQUENCY (f): number of crests that pass through a point each second. It is measured in units of hertz (Hz), which are the number of cycles per second.
AMPLITUDE: A measure of the strength of the wave.
SPEED (s): how fast the wave pattern moves For any wave: s = f 

24. The speed of light is a constant: s = c !!!
Light as a Wave
The speed of light is a constant: s = c !!!
Therefore, for light: f  = c
The higher f is, the smaller  is, and vice versa.
In the visible part of the spectrum, our eyes recognize f (or ) as color!

25. Light as a Particle
Light can also be treated as photons – packets of energy.
The energy carried by each photon depends on its frequency (color)
Energy: E = hf = hc/  [“h” is called Planck’s Constant]
Shorter wavelength light carries more energy per photon.

26. The Electromagnetic Spectrum
lower energy
higher energy

27. Light as Information Bearer
Spectrum: light separated into its different wavelengths.
Spectroscopy: The quantitative analysis of spectra
The spectrum of an object can reveal the object’s:
Composition
Temperature
Velocity

28. “Matter” and Light

29. Four Ways in Which Light can Interact with Matter
emission – matter releases energy as light
absorption – matter takes energy from light
transmission – matter allows light to pass through it
reflection – matter reflects light

30. Emission, absorption, transmission, reflection
The type of interaction between light and matter is determined by characteristics of the “matter” and by the wavelength of light.

31. A Brief Review of “Matter”

32. Atom nucleus electron p+ e- n
(proton,neutrons)
electron p+ e- n
Number of protons determines the element
Number of neutrons determines the isotope
10,000,000 atoms can fit across a period in your textbook.
The nucleus is nearly 100,000 times smaller than the entire atom (if atom filled the classroom auditorium, the nucleus would be barely visible at its center).
Although it is the smallest part of the atom, most of the atom’s mass is contained in the nucleus.

33. Electrons do not “orbit” the nucleus; they are “smeared out” in a cloud which give the atom its size.
Incorrect view
better view

34. The number of protons determines the type of element

35. Hydrogen e- p+ atomic number (protons) = 1
atomic mass number (protons + neutrons)= 1

36. Helium e- p+ p+ n n e- atomic number (protons) = 2
atomic mass number (protons + neutrons)= 4

37. Atomic Number. Element. 1. Hydrogen (H). 2. Helium (He). 3
Atomic Number Element Hydrogen (H) Helium (He) Lithium (Li) Beryllium (Be) Boron (B) Carbon (C) Nitrogen (N) Oxygen (O)

38. Relative abundances of elements in the universe

39. Every element has different “isotopes” same number of protons (same element) different number of neutrons

40. Hydrogen isotope of hydrogen p+ e- atomic number (protons) = 1
atomic mass number (protons + neutrons)= 1

41. Hydrogen isotope of hydrogen p+ n e- atomic number (protons) = 1
(Deuterium)
isotope
of hydrogen p+ n e-
atomic number (protons) = 1
atomic mass number (protons + neutrons)= 2

42. Hydrogen isotope of hydrogen p+ n n e- atomic number (protons) = 1
(Tritium)
isotope
of hydrogen p+ n n e-
atomic number (protons) = 1
atomic mass number (protons + neutrons)= 3

43. Every element has multiple isotopes
Every element has multiple isotopes (same number of protons, different numbers of neutrons) some of which may not be stable (“radioactive”)
Carbon-14 half-life = 5,730 yrs

44. Unstable (“radioactive”) isotopes “decay”, producing a new type of atom, i.e., an atom of a different element, or a different isotope of the original element.
One half of the atoms of an unstable isotope decay in one “half-life” of that isotope.

45. Three isotopes of Carbon, two stable, one unstable.
5730 yrs
14C  14N + electron + antineutrino + energy
Initial Mass (14C) > Final Mass (14N + electron + antineutrino)
 difference in mass is converted into energy: E = mc2

46. What if an electron is missing?
ion e- p+ p+ n n
atomic number = 2
He+1
atomic mass number = 4

47. What if two or more atoms combine to form a particle?
molecule
H2O (water) p+ p+
8p+
Sharing of electrons (chemistry) is involved in the construction of molecules 8n