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Architecture of the Universe The size of a person is used as a reference
Small Scale Structure Elementary Particles (Quarks, Electrons) Composite Particles (Protons, Neutrons) Atomic Nuclei (Chemical Elements) Atoms and Ions Molecules
Large Scale Structure Solar System Solar Neighborhood Galaxy (Milky Way) Galaxy Cluster / Group Supercluster
Universe
ELEMENTARY PARTICLES Smallest particles in nature
- make up everything in the universe
Particle accelerators
CERN (France, Switzerland)
Particle Trails
12 Elementary Particles in nature
- have no internal structure
- have no intrinsic size
Measurable Properties:
- Mass: “quantity of matter” - not the same as weight or size
- Electric Charge: (positive or negative)
Only three are important for “normal” matter Up Quark, Down Quark, Electron
Other important particles (inside stars) Neutrino (three types)
Name
Structure
Mass*
Charge*
Up Quark
none
1/3
+ 2/3
Down Quark
none
1/3
- 1/3
Electron
none
0.0005
-1
* - atomic units * 1 amu = 1.67 x 10-27 kg
COMPOSITE PARTICLES (“HADRONS”)
Formed from groups of three quarks
* atomic units
Name Structure Mass* Electric Charge*
Proton (p or 1H)
u u
d
1.0
+1.0
Neutron ( n )
d d
u
1.0021
0
CHEMICAL ELEMENTS (Nucleus)
Formed from Protons and Neutrons
Name
Structure
Mass*
(A)
Electric
charge (Z)
Hydrogen (1H)
p
1 +1
Helium (4He)
p p
n n
4 +2
Carbon (12C)
p p p p p p
n n n n n n
12 +6
Total Charge of Nucleus (“atomic number”)
- total number of protons in nucleus
-uniquely defines an element
For example: any nucleus with 6 protons is Carbon
6p + 6n 12C (most common form)
6p + 7n 13C 6p + 8n 14C
12C, 13C, 14C are isotopes of Carbon
Symbols (Writing/Print) (Periodic Table only)
Atomic Mass (A) (Z)
X X Atomic Number (Z) * (A)
(* often omitted)
Link to Periodic Table: http://science.widener.edu/~svanbram/ptable_6.pdf
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Example: Iron 56Fe Fe 56
ATOMS AND IONS Formed from a nucleus and electrons
Name Structure Mass Charge
Hydrogen Atom (H)
1 0
Helium Atom (He)
4 0
Helium Ion (He+)
4 +1
Ion: Total charge (nucleus + electrons) 0
MOLECULES
Formed from atoms and ions. Very rare
- need lots of atoms/ions close together - need low temperatures
- less than ~3000 K (~5000oF)
Name Structure Mass Charge
Oxygen molecule (O2)
O O 32 0
Water (H2O)
O
H H 18 0
Ethanol (C2H6O)
H H
H C C O H
H H
46 0
MOLECULES
Our World
Forces of Nature
Force - describes how objects interact -objects can only attract or repel each other
- account for structure in the universe on all scales
Four Fundamental Forces
Gravitational Force
Electromagnetic Force
Strong (Nuclear) Force
Weak (Nuclear) Force
1. Gravitational Force (1685)
- only attractive
- affects all types of particles
- infinite range
- the weakest of the four forces
- dominates all large scale structure
2. Electromagnetic (EM) Force (1865)
- attractive or repulsive
- only affects particles with an electric charge
- infinite range
- stronger than gravitational force - second strongest overall
- dominates from atomic to human
3. Strong (Nuclear) Force (1935)
- attractive
- affects quarks (and composite particles) but not electrons
- short range
- strongest force
- dominates over smallest size scales up to the atomic nucleus
4. Weak (Nuclear) Force (1956)
- changes one elementary particle into another
- explains radioactivity
- affects all types of particles
- very short range
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Dominant Forces on All Scales
Structure
Dominant Force
Elementary Particles
Composite Particles
Strong (Nuclear) orce
Atomic Nuclei
Atoms and Ions Electromagnetic
Molecules Solar System
Gravitational Force
Solar Neighborhood
Milky Way Galaxy
Gravitational Force
The Local Group
The Local (Virgo) Supercluster
The Entire Universe