1. Homework page 100 exercises 1-11 Continue reading through chapter 3

2. © 2004 Pearson Education Inc., publishing as Addison-Wesley

3. An atom consists of a small, dense nucleus surrounded by electronsp+ n
An atom consists of a small, dense nucleus surrounded by electrons
proton
neutron

4. The “size” of an Atom
Although it is the smallest part of the atom, most of the atom’s mass is contained in the nucleus.
The electrons do not “orbit” the nucleus; they are “smeared out” in a cloud which give the atom its size.

5. Hydrogen p+ e-
atomic number = 1
atomic mass number = 1

6. Helium p+ p+ n n e- e-
atomic number = 2
atomic mass number = 4

7. Hydrogen Deuterium isotope p+ e- n atomic number = 1
atomic mass number = 2

8. The particles in the nucleus determine the element & isotope.

9. atomic number = #protons
atomic mass no. = #protons + #neutrons

10. Note on Energy on Atomic Scales:
We use a smaller unit of Energy on quantum scales..
The electron-volt (eV) = 1.602x10-19 J
= J
This is because atomic energies are incredibly small…
for a typical football player:

11. Hydrogen … En = -13.6 / n2 n En (eV) 1 -13.60 2 -3.40 3 -1.51 4 -0.85 …
n=1
n=4
n=3
n=2
En = / n2

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

13. What if two or more atoms combine to form a particle?
molecule p+ p+
8p+ 8n
H2O (water)

14. Phases of Matter the phases
solid
liquid
gas
plasma
depend on how tightly bound the atoms and/or molecules are
As temperature increases, these bonds are loosened:

15. Electron Energy
Electrons that are bound in atoms can gain or lose energy.
When electrons have the lowest energy possible, we say the atom is in the ground state.
When electrons have more energy than this, the atom is in an excited state.
When electrons gain enough energy to escape the nucleus, the atom is ionized.

16. Electron Energy Levels
Electrons can not have just any energy while orbiting the nucleus.
Only certain energy values are allowed.
Electrons may only gain or lose specific amounts of energy.
Each element (atom and ion) has its own distinctive set or pattern of energy levels.
This diagram depicts the energy levels of Hydrogen. eV eV eV eV eV

17. n=2
n=3
Photons are created when an electron jumps from one energy level to another

19. Important years for astronomy
Levoisier 1789; mendeleev 1869; Rydberg 1888

20. En = -13.6 / n2 (eV) (Rydbergs formula) …
n En (eV) …
En = / n2 (eV)
(Rydbergs formula)
DE(3 g 2) = E3-E2 =-1.51-(-3.40) = 1.89 eV

21. Objects in Motion
speed – rate at which an object moves, i.e. the distance traveled per unit time [m/s; mi/hr]
velocity – an object’s speed in a certain direction, e.g. “10 m/s moving east”
acceleration – a change in an object’s velocity, i.e. a change in either speed or direction is an acceleration [m/s2]

22. As objects fall, they accelerate.
The acceleration due to Earth’s gravity is 10 m/s each second, or g = 10 m/s2.
The higher you drop the ball, the greater its velocity will be at impact.

23. You may remember my experiment…
t=0s;
v=0m/s
t=1s;
v=10 m/s
t=2s; v=20m/s
You may remember my experiment…

24. The Acceleration of Gravity (g)
Galileo measured g to be about 10 m/s2
He demonstrated that g is the same for all objects, regardless of their mass!
This was confirmed by the Apollo astronauts on the Moon, where there is no air resistance.
Galileo was right!

25. Universal Laws of Motion
“If I have seen farther than others, it is because I have stood on the shoulders of giants.”
Sir Isaac Newton (1642 – 1727)
Physicist

26. Sir Isaac Newton (1642-1727) Perhaps the greatest genius of all time
Invented the reflecting telescope
Invented calculus
Connected gravity and planetary forces
Philosophiae naturalis principia mathematica