Martin D. Weinberg UMass Astronomy astron100 …courses.umass.edu/astron100-mdw/lectures/lec08.pdf · Martin D. Weinberg UMass Astronomy [email protected] September

Read: Chap 5, review for Exam 09/25/14 – slide 1

A100–Exploring the Universe: Light and Matter

Martin D. Weinberg

UMass Astronomy

[email protected]

September 25, 2014

Announcements

⊲ Announcements

Summary

What is the structureof matter?

Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


First in-class exam on THURSDAY!

⊲ Multiple choice (40-50 questions)

⊲ Covers Chapters 1,3,4,5

⊲ Use Mastering to help you study!!

Announcements

⊲ Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum






Today: More on Light and Matter (LIGHT, Chap. 5)

⊲ What is the structure of matter?

⊲ What are the phases of matter?

⊲ How is energy stored in atoms?

⊲ What are the three basic types of spectra?

⊲ How does light tell us what things are made of?

Announcements

⊲ Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum






Today: More on Light and Matter (LIGHT, Chap. 5)

⊲ What is the structure of matter?

⊲ What are the phases of matter?

⊲ How is energy stored in atoms?

⊲ What are the three basic types of spectra?

⊲ How does light tell us what things are made of?

Questions?

Properties of Light: Summary

Announcements

⊲ Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Particle properties

⊲ Travels in straight lines (bullets)

⊲ “Rays” are parallel far from source

⊲ E = hν

Wave properties

⊲ “Rainbow” spectrum

⊲ Interference

Light is electromagnetic radiation

Wave-Particle Duality: light has both wave-like and

particle-like properties!

Thought question

Announcements

⊲ Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


The higher the photon energy . . .

the longer its wavelength.

the shorter its wavelength.

energy is independent of wavelength.

Thought question

Announcements

⊲ Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum






Thought question

Announcements

⊲ Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum






λν = c

Thought question

Announcements

⊲ Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum






λν = c =⇒ ν =

c

λ

Thought question

Announcements

⊲ Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum






λν = c =⇒ ν =

c

λ

E = hν

Thought question

Announcements

⊲ Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum






λν = c =⇒ ν =

c

λ

E = hν =

hc

λ

What is the structure of matter?

Announcements

Summary

⊲

What is thestructure ofmatter?

Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


[Atom] [Electron cloud] [Nucleus]

Atomic terminology

Announcements

Summary


⊲Atomicterminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Atomic Number = # of protons in nucleus

Atomic Mass Number = # of protons + neutrons

Molecules: consist of two or more atoms (H2O,CO2)

Atomic terminology

Announcements

Summary



4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18hydrogen helium

1 2

H He1.00794(7) Key: 4.002602(2)

lithium beryllium element name boron carbon nitrogen oxygen fluorine neon

3 4 atomic number 5 6 7 8 9 10

Li Be symbol B C N O F Ne6.941(2) 9.012182(3) 2003 atomic weight (mean relative mass) 10.811(7) 12.0107(8) 14.0067(7) 15.9994(3) 18.9984032(5) 20.1797(6)

sodium magnesium aluminium silicon phosphorus sulfur chlorine argon

11 12 13 14 15 16 17 18

Na Mg Al Si P S Cl Ar22.989770(2) 24.3050(6) 26.981538(2) 28.0855(3) 30.973761(2) 32.065(5) 35.453(2) 39.948(1)

potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr39.0983(1) 40.078(4) 44.955910(8) 47.867(1) 50.9415(1) 51.9961(6) 54.938049(9) 55.845(2) 58.933200(9) 58.6934(4) 63.546(3) 65.38(2) 69.723(1) 72.64(1) 74.92160(2) 78.96(3) 79.904(1) 83.798(2)

rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe85.4678(3) 87.62(1) 88.90585(2) 91.224(2) 92.90638(2) 95.96(2) [98] 101.07(2) 102.90550(2) 106.42(1) 107.8682(2) 112.411(8) 114.818(3) 118.710(7) 121.760(1) 127.60(3) 126.90447(3) 131.293(6)

caesium barium lutetium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon

55 56 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn132.90545(2) 137.327(7) 174.9668(1) 178.49(2) 180.9479(1) 183.84(1) 186.207(1) 190.23(3) 192.217(3) 195.078(2) 196.96655(2) 200.59(2) 204.3833(2) 207.2(1) 208.98038(2) [209] [210] [222]

francium radium lawrencium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium ununbium ununtrium ununquadium ununpentium ununhexium ununseptium ununoctium

87 88 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118

Fr Ra Lr Rf Db Sg Bh Hs Mt Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo[223] [226] [262] [267] [268] [271] [272] [270] [276] [281] [280] [285] [284] [289] [288] [293] — [294]

lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium

57 58 59 60 61 62 63 64 65 66 67 68 69 70

Lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb138.9055(2) 140.116(1) 140.90765(2) 144.24(3) [145] 150.36(3) 151.964(1) 157.25(3) 158.92534(2) 162.500(1) 164.93032(2) 167.259(3) 168.93421(2) 173.054(5)

actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium

89 90 91 92 93 94 95 96 97 98 99 100 101 102

Actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No[227] 232.0381(1) 231.03588(2) 238.02891(3) [237] [244] [243] [247] [247] [251] [252] [257] [258] [259]

WebElements: the periodic table on the world-wide webhttp://www.webelements.com/

Element symbols and names: symbols, names, and spellings are recommended by IUPAC (http://www.iupac.org/). Names are not yet proposed for the elements beyond 111 - those used here are IUPAC’s temporary systematic names (Pure & Appl. Chem., 1979, 51, 381–384). In the USA and some other countries, the spellings

aluminum and cesium are normal while in the UK and elsewhere the usual spelling is sulphur.

Atomic weights (mean relative masses): Apart from the heaviest elements, these are IUPAC 2007 values (Pure & Appl. Chem., 2007, in press). Elements with values given in brackets have no stable nuclides and are represented by integer values for the longest-lived isotope known at the time writing.

The elements thorium, protactinium, and uranium have characteristic terrestrial abundances and these are the values quoted. The last significant figure of each value is considered reliable to ±1 except where a larger uncertainty is given in parentheses.

Periodic table organisation: for a justification of the positions of the elements La, Ac, Lu, and Lr in the WebElements periodic table see W.B. Jensen, “The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table”, J. Chem. Ed., 1982, 59, 634–636.

Group labels: the numeric system (1–18) used here is the current IUPAC convention. For a discussion of this and other common systems see: W.C. Fernelius and W.H. Powell, “Confusion in the periodic table of the elements”, J. Chem. Ed., 1982, 59, 504–508.

©2007 Dr Mark J Winter [WebElements Ltd and University of Sheffield]. All rights reserved. For updates to this table see http://www.webelements.com/nexus/Printable_Periodic_Table. Version date: 21 September 2007.

Atomic terminology

Announcements

Summary



4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Atomic terminology

Announcements

Summary



4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Isotope: same # of protons but different # of neutrons.

(4He, 3He)

4 Fundamental Forces (aside)

Announcements

Summary


Atomic terminology

⊲ 4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Physicists have identified four natural forces

1. Gravity

Holds the Sun and planets together in the solar

system

Holds stars together in galaxies

Things fall “down” on Earth

4 Fundamental Forces (aside)

Announcements

Summary


Atomic terminology

⊲ 4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Physicists have identified four natural forces

1. Gravity

Holds the Sun and planets together in the solar

system

Holds stars together in galaxies

Things fall “down” on Earth

2. Electromagnetism: a force between objects with electric

charge

Holds atoms together

Responsible for chemical reactions

Friction of book on table

Magnets

Fundamental Forces

Announcements

Summary


Atomic terminology

⊲ 4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


3. Strong force

Holds nuclei of atoms together

Generation of energy in stars, supernovae

Power, bombs

Fundamental Forces

Announcements

Summary


Atomic terminology

⊲ 4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


3. Strong force

Holds nuclei of atoms together

Generation of energy in stars, supernovae

Power, bombs

4. Weak force

Radioactive decay

Also energy in stars, supernovae

Fundamental Forces


Interaction Current Theory Strength Range (m)

Strong Quantum chromodynamics (QCD) 1038 10−15

Electromagnetic Quantum electrodynamics (QED) 1036 (Infinite)Weak Electroweak Theory 1025 10−18

Gravitation General Relativity (GR) 1 (Infinite)

Phases & Pressure

Announcements

Summary


Atomic terminology

4 forces

⊲ Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Phase of a substance depends on both temperature and

pressure

Often more than one phase is present

Phases & Pressure

Announcements

Summary


Atomic terminology

4 forces


Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Example: familiar phases (of water)

Solid (ice)

Liquid (water)

Gas (water vapor)

Phases of same material behave differently because of

differences in chemical bonds

Phases & Pressure

Announcements

Summary


Atomic terminology

4 forces


Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Example: familiar phases (of water)

Solid (ice)

Liquid (water)

Gas (water vapor)

Phases of same material behave differently because of

differences in chemical bonds

Less familiar phase:

Ionized (plasma), no chemical bonds

Phases & Pressure

Announcements

Summary


Atomic terminology

4 forces


Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Ionization: Stripping of electrons,

changing atoms into plasma

Dissociation: Breaking of molecules

into atoms

Evaporation: Breaking of flexible

chemical bonds, changing liquid into

solid

Melting: Breaking of rigid chemical

bonds, changing solid into liquid

Thermal or Blackbody Radiation


Electromagnetic radiation is caused by moving charges

⊲ Electrons in a radio antenna

⊲ Accelerated electrons in an X-ray tube

Most material objects are made charged particles



Electromagnetic radiation is caused by moving charges

⊲ Electrons in a radio antenna

⊲ Accelerated electrons in an X-ray tube

Most material objects are made charged particles

The temperature of an object proportional to vibration of charges

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5 6 7 8

Fra

ctio

n w

ith g

iven

spe

ed

Speed

cold

warm

hot

Maxwell Distribution

[demo]


Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

⊲ Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Examples:

⊲ Hot objects glow! (Fireplace, stove top, . . . )

⊲ Cooler objects like the human body are emitting

radiation as well, though mostly at longer

wavelengths, in the infrared.


Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure


Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Examples:

⊲ Hot objects glow! (Fireplace, stove top, . . . )

⊲ Cooler objects like the human body are emitting

radiation as well, though mostly at longer

wavelengths, in the infrared.



Planck (1900) was trying to understand the nature of radiation that filled

an enclosure that had come to equilibrium

This emission of radiation that de-

pends on an objects temperature is

called thermal or blackbody radia-

tion

A perfect blackbody reflects no light

(it’s only truly black at 0◦ K)

When heated, a blackbody glows

with a continuous spectrum which

depends only on its temperature


Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure


Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Planck measured the amount of energy in the radiation

as a function of wavelength

Their results could be displayed as a kind of histogram,

with energy plotted against small wavelength intervals

(a distribution)

Shapes of the curves depended only on the temperature

of the enclosure, and not on the material inside

This energy distribution became known as the

Universal Planck Radiation Law


Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure


Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Distribution for different T


Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure


Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Distribution for the Sun


Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure


Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Wien’s Law

λpeak =0.29

T (◦ K)cm

=2.9× 10−3

T (◦ K)m

=2.9× 106

T (◦ K)nm

Allows us to estimate the temperature of celestial bodies!

Spectra of elements

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

⊲Spectra ofelements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Kirchoff & Bunsen (c1850): Each chemical element

produces a unique set of spectral lines

Not a Planck spectrum!

Types of Spectra

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

⊲ Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Kirchoff & Bunsen cataloged spectra of all known

elements

Observed spectrum of Sun

⊲ Part of solar spectrum (upper)

⊲ Iron lines in lab (lower)

Pattern matches elements whether dark or light lines

Lines found in Sun not known on Earth:

discovery of Helium!

How is energy stored in atoms?

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

⊲ Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Electrons in atoms are restricted to particular energy

levels

Internal energy

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

⊲ Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Energy Level Transitions

The only allowedchanges in en-ergy are thosecorrespondingto a transitionbetween energylevels

Internal energy

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

⊲ Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum



Disallowed!


Internal energy

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

⊲ Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum



Disallowed! Allowed!


Chemical fingerprints

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

⊲ Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Downward transitions

produce a unique pattern

of emission lines

Because those atoms can

absorb photons with those

same energies, upward

transitions produce a pat-

tern of absorption lines at

the same wavelengths

[demo]

Chemical fingerprints

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

⊲ Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


Each atom has unique spectral figureprint

Kirchhoff’s Laws

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

⊲ Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

Solar spectrum


1. A dense (opaque) hot object emits a continuous

spectrum

2. A cool tenuous cloud emits discrete spectral lines

3. A hot opaque object viewed through a cool cloud shows

a continuous spectrum with absorption lines

Virtually every astronomical observation fits in one of these

categories.

Types of Spectra

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

⊲ Types of Spectra

Continuous spectrum

Solar spectrum


Continuous spectrum

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

⊲Continuousspectrum

Solar spectrum


The spectrum of a common (incandescent) light bulb

spans all visible wavelengths, without interruption

Example: Solar spectrum

Announcements

Summary


Atomic terminology

4 forces

Phases & Pressure

Thermal radiation

Spectra of elements

Types of Spectra

Internal energy

Kirchhoff’s Laws

Types of Spectra

Continuous spectrum

⊲ Solar spectrum


Documents

Martin D. Weinberg UMass Astronomy astron100 …courses.umass.edu/astron100-mdw/lectures/lec08.pdf · Martin D. Weinberg UMass Astronomy [email protected] September