Nuclear Chemistry• Brief history of nuclear related discoveries

– Electron, proton, neutron

• Nuclear transformations– Natural radioactivity– Half Life, carbon dating– Nuclear chemistry equations– Chain reaction, atom bomb

• Applications– Nuclear reactors– Radioisotopes

• Accidents– 3-mile Island (USA), Chernobyl (USSR), Japan– Potassium Iodide protection

Atomic number

• Atomic Number (and element number)– Number protons = number electrons = “Z”

• Atomic Mass Number– Total Number of Protons defining the element = Z– Total number of Neutrons in element nucleus = N– Total mass of nucleus = A = Z + N– Electron mass ignored 1/1836 =0.054% (considered negligible)

• Isotopes– Same atomic number, different number of neutrons– Large variations of isotopes between elements – Isotope significance (e.g. U-235 vs U-238, C-14 vs C-12)

• Atomic Weight (most often used)– Weighted average of isotope masses– What’s on the periodic chart

Atomic versus NuclearWhat’s the Difference?

• Atomic properties are those of an atom– Chemical reactions (gain/loss of electrons)– Emission of light (electron orbit jumps)– Bonds between elements (covalent, ionic)

• Nuclear properties are within the atom– Construction of nucleus (electrons, protons)– Radioactive disintegration– Fission/fusion of nuclei, element conversion

Protons & Neutrons• Protons at core of Element, with positive charge

– Positive charge balances negative electron charge– Element Atomic Number = number of Protons in that element– Total number protons = nuclear charge = “Z”

• Electron has least mass– One electron = 0.910938291*10-27 grams

• Proton has mass of 1836 times that of electron– One proton = 1.6726218*19-24 grams

• Neutron slightly heavier than Proton … but no charge– One neutron = 1.6749286*10-24 grams

• Isotopes– Same Element and atomic number, different number of neutrons– Approximately the same number of neutrons as protons– Large variations between elements

• Atomic Weight (most often used)– Weighted average of isotope masses– What’s on the periodic chart

Isotopes• Same element can have different mass

– Same # of protons• Protons determine # of electrons for bonding• Neutral element has equal # protons and electrons

– variable # of neutrons• No charge but mass about same as proton• No influence in chemical reactions• “goes along for the ride”

– Show slide of isotopes• Thousands of isotopes for ≈110 elements

Weighted Atomic Mass (natural values)• Lots of isotopes of Uranium exist, all different masses

– Most prevalent isotope is U-238 at 99.283%– Most useful isotope is U-235 at 0.711%– Other isotopes rather rare, relatively insignificant

• “Weighted Average” recognizes quantity– Sum of mass contributions = the weighted average value– This is what we see on the periodic charts.

natural UraniumAtomic Mass PerCent Contribution

U-238 238 99.283% 236.29354U-235 235 0.711% 1.67085Total 99.994%

Weighted Average 237.96439

Nuclear Changes

7

• Nuclear reaction: A reaction that changes an atomic nucleus, usually causing the change of one element into another. A chemical reaction never changes the nucleus.

• Different isotopes of an element have essentially the same behavior in chemical reactions but often have completely different behavior in nuclear reactions.

• The rate of a nuclear reaction is unaffected by a change in temperature or pressure (within the range found on earth) or by the addition of a catalyst.

• The nuclear reaction of an atom is essentially the same whether it is in a chemical compound or in an uncombined, elemental form.

• The energy change accompanying a nuclear reaction can be up to several million times greater than that accompanying a chemical reaction.

Conservation of Energy

• Chemical change • Reactions cause change, but not total amount of energy • Total energy the same before & after reaction

• Different forms of energy can be inter-converted• Potential energy into kinetic (roller coaster)• Chemical Bonds broken generate heat

– Burning wood, gasoline

• Reaction simply rearranges the relationships• Conversion may happen between solid, liquids, gases

– Quantity of element atoms will be the same

– Energy insignificant compared to mass• Generally ignored in chemical formulas

Conservation of Mass (among other things)

• Conservation rules:– Sum of Products = Sum of Ingredients

• Numerous conservation rule examples …– Conservation of Mass, – Conservation of Energy, – Conservation of Momentum, – Conservation of Angular Momentum

– Chemical change cannot create or destroy mass • Reactions cause change in form but not total amount • Total mass the same before and after reaction• Mass is invariant to chemical reactions

Conservation of Mass (and other things)

Einstein would disagree …– Mass is convertible to energy and vice versa

• Applies particularly to nuclear reactions• Escaping radiation equivalent to some mass loss

– Conversion ratio is enormous, E=mC2

• LOT of energy equivalent to small amount of mass

– Practical impact in non-nuclear chemistry• Ignore radiation for mass conservation• Ignore heat for mass conservation

11

11.1 Nuclear Reactions• The atomic number, written below and to the left of the

element symbol, gives the number of protons in the nucleus and identifies the element.

• The mass number, written above and to the left of the element symbol, gives the total number of nucleons, a general term for both protons (p) and neutrons (n).

• The most common isotope of carbon, for example, has 12 nucleons: 6 protons and 6 neutrons:

Writing Nuclear Reactions

• “stacked” numbers difficult to write using a word processor

• Alternative is “front and back” values

–Carbon 14 = 6C14

– Front value is atomic number Z– Back value is atomic mass A

Cathode Rays, Crookes 1895Early investigator of radiation inside electrical discharge tubes,

eventually leading to CRT (Television) tubes. He was one of the first to experiment with radioactivity and its ability to make certain minerals

glow. He also invented the ”radiometer” still in use as an educational toy.

60 years of breakthroughs• 1884 - Chemistry innovations, 56 theses, Arrhenius

• 1888 - Proton Discovery, Goldstein

• 1895 – X-Ray discovery, Roentgen

• 1896 - Radioactivity Discovery, Baqerel

• 1897 - Electron Discovery, J.J. Thompson

• 1905 - Radioactive Element separation, Curie

• 1905 - Equivalence of mass & energy E=mC2, relativity, photoelectric effect, A. Einstein

• 1916 - general relativity, proven in 1919, A. Einstein

• 1932 - Neutron Discovery, Chadwick

• 1933 - Nuclear chain reaction proposed, Szilard

• 1938 - Nuclear fission discovered

• 1942 - First operational nuclear reactor, Fermi

• 1945 - First warfare use of nuclear energy

15

11.2 Discovery and Nature of Radioactivity

• In 1896, the French physicist Henri Becquerel noticed a uranium-containing mineral exposed a photographic plate that had been wrapped in paper.

• Marie and Pierre Curie investigated this new phenomenon, which they termed radioactivity: The spontaneous emission of radiation from a nucleus.

• Ernest Rutherford established that there were at least two types of radiation, which he named alpha and beta. Shortly thereafter, a third type of radiation was found and named for the third Greek letter, gamma.

Equivalence of Mass & EnergyAlbert Einstein’s famous equation E=mc2

E=mc2, so light energy has mass Although small, mass of light is an important consequence

Space distortion due to massGeneral Relativity predicted light deflection by mass in

1916, proven by experiment in 1919

Gravity Well or “Black Hole”space is so distorted that light cannot pass nearby, a

consequence of general relativity

Mass into Energy

• Enormous ratio between mass & Energy– c = 3*10^8 meters/sec– c2 = 9*10^16 meters2/sec2

• How much energy is that ?– 1 gram U235 converts to 3.4*10^8 kcal– Hiroshima bomb converted only a few grams

21

When passed between two charged plates: • Alpha rays, helium nuclei (He+2 ), bend toward the

negative plate because they have a positive charge. • Beta rays, electrons (e- ), bend toward the positive plate

because they have a negative charge. • Gamma rays, photons (), do not bend toward either

plate because they have no charge.

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• Alpha rays move at ~0.1c (”c” is speed of light), stopped by a few sheets of paper or by the top layer of skin.

• Beta rays move at up to 0.9c and have about 100 times the penetrating power of particles. A block of wood or heavy clothing is necessary to stop rays.

• Gamma rays move at c and have about 1000 times the penetrating power of rays. A lead block several inches thick is needed to stop rays.

Baquerel – observed radioactivity 1896Photographic plate accidentally exposed by Uranium

Baquerel is SI unit of radiation, Bq = disintegrations/sec1 Curie = radiation from 1 gram of Radium = 3.7*10^10 Bq

ELECTRON - J.J. Thompson 1897found a new particle “boiling off” a heated filament which had <1/1000 mass of hydrogen. It had a negative charge

by its magnetic and/or electrostatic deflection. Using similar apparatus he discovered isotopes of the same element with different mass, which led to science of mass spectrometry

Marie & Pierre Curie, 1905Separated tons of mineral pitchblende to discover and isolate Radium, and polonium (named for Poland). The

standard measure for radioactivity is the Curie = Ci

PROTON, Goldstein in1888Used high voltage to ionize gases, accelerating particles

through holes in cathode, causing “canal rays” (trails looked like canals). Particles were positive. Hydrogen particles

later identified as protons by Rutherford in 1919

NEUTRON, Chadwick 1932observed a new form of penetrating radiation,

which had no charge (not protons or electrons)

NEUTRINOPredicted by

Wolfgang Pauli in 1930, based on

conservation discrepancies.

the “little neutron” Indirectly

observed in 1942 and1946 via

interactions with other particles,

directly observed in 1972 “bubble

chamber”

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11.3 Stable and Unstable Isotopes• Every element in the periodic table has at least one

radioactive isotope, or radioisotope, and more than 3300 radioactive isotopes are known.

• Their radioactivity is the result of having unstable nuclei. Radiation is emitted when an unstable radioactive nucleus, or radionuclide, spontaneously changes into a more stable one.

• There are only 264 stable isotopes among all the elements.

• All isotopes of elements with atomic numbers higher than that of bismuth (83) are radioactive.

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• For elements in the first few rows of the periodic table, stability is associated with a roughly equal number of neutrons and protons.

• As elements get heavier, the number of neutrons relative to protons in stable nuclei increases.

• Lead-208, for example, the most abundant stable isotope of lead, has 126 neutrons and 82 protons in its nuclei.

Radioactivity

• Emissions from Pitchblende (uranium ore)– Found to expose photographic film

• 3 common types of nuclear radiation– Alpha (α), helium nuclei particle, 2He4 = 2p+2n

• Very strong but not very penetrating

– Beta (β), an electron particle, -1e0

• Mildly penetrating, stopped by thick paper

– Gama (γ), radiation similar to X-Ray• Very penetrating, used for imaging

Radioactivity

• Results from unstable elements• Heavy elements formed inside stars

– Formed and stable at extreme temperatures– Unstable and disintegrate at earth temperatures

• Half-Life– Time it takes for ½ of material to disintegrate– Uranium 238 is 4.5 billion years, same as earth’s age

• There was twice as much uranium when earth formed• A non-linear scale (e.g ½ of ½, etc)• A natural nuclear reactor happened in Okla, Africa

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11.4 Nuclear Decay

• Nuclear decay: The spontaneous emission of a particle from an unstable nucleus.

• Transmutation: The change of one element into another.

• The equation for a nuclear reaction is not balanced in the usual chemical sense because the kinds of atoms are not the same on both sides of the arrow. A nuclear equation is balanced when the number of nucleons and the sums of the charges are the same on both sides.

Nuclear Decay

• Decrease in atomic number– Loss of alpha particle with positive charge

• Mass of 2 protons and 2 neutrons• Loss of 2 protons reduces element # by 2

– Uranium 92U238 into Thorium 90Th234 + 2He4

• Increase in atomic number– Loss of electron with negative charge

• Charge of nucleus increases by 1• Next higher element formed

– Thorium 90Th234 Proactinium 91Pa234 + -1 e0

– Proactinium 91Pa234 Uranium 92U234 + -1 e0

Alpha Decay a common event, new element with lower atomic number (by two) is formed

• Unstable nucleus emits a helium nuclei

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• During alpha emission, the nucleus loses two protons and two neutrons.

• Emission of an particle from an atom of uranium-238 produces an atom of thorium-234.

Proton Emissionloss of positive charge reduces atomic number by 1

Neutron Emission

Beta ParticleUnstable isotope emits electron having negative charge, nucleus of parent changes charge in the other direction, creating a new element. Example is Carbon-14 used for dating historical objects. Note another particle with zero mass and charge, the “Neutrino” … more about that later

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• Electron capture, symbolized E.C., is a process in which the nucleus captures an inner-shell electron from the surrounding electron cloud, thereby converting a proton into a neutron.

• The conversion of mercury- 197 into gold-197 is an example of electron capture.

Electron CaptureInner orbit electron can be “snagged” by nucleus

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• Beta emission involves the decomposition of a neutron to yield an electron and a proton.

• Iodine-131, a radioisotope used in detecting thyroid problems, undergoes nuclear decay by emission to yield xenon-131.

What about anti-matter?• 1928 prediction by Paul Dirac that wave

equations allow for negative matter

• Anti-particles are the same as conventional except for charge– Electron (e-) Positron (e+), 2008-LNL– Proton (p+) Anti-Proton (p-),1955-UCB– Hydrogen Anti-Hydrogen; 1995-CERN

• Matter+Antimatter pure energy– Just like they say in Star Trek !

Anti-Particles, Anti-Matter

• In 1928 Paul Dirac predicted that all particles should have opposites called anti-particles.

• The first of these was discovered in 1932 by Carl Anderson. This was an electron with a positive electric charge (+1). This particle is the anti-electron (also called a positron). It is identical in every respect to the electron apart from its electric charge.

• When an electron and positron come into contact, they mutually annihilate each other producing a flood of energy in accordance with Einstein's famous equation, E=mC2

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• Positron emission involves the conversion of a proton in the nucleus into a neutron plus an ejected positron.

• A positron has the same mass as an electron but a positive charge.

• Potassium-40 undergoes positron emission to yield argon-40.

Positron EmissionUnstable nuclei can also emit a positive electron, a form of

“anti-matter” which turns into energy upon meeting it’s opposite. Mass and charge must balance

47

• Emission of rays causes no change in mass or atomic number.

emission usually accompanies emission of other rays but it is often omitted from nuclear equations.

• Their penetrating power makes them both dangerous to humans and useful in medical applications.

48

11.5 Radioactive Half-Life• Rates of nuclear decay are measured in units of half-

life , defined as the amount of time required for one-half of the radioactive sample to decay.

• Each passage of a half-life causes the decay of one half of whatever sample remains. The half-life is the same no matter what the size of the sample, the temperature, or any other external conditions.

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All nuclear decays follow the same curve, 50% of the sample remains after one half-life, 25% after two half-lives, 12.5% after three half-lives, and so on.

Carbon-14 Dating

• Carbon14 discovered in 1940 at UC– Formed in upper atmosphere from nitrogen– Solar neutrons convert nitrogen to carbon-14– Carbon-14 becomes carbon dioxide– Carbon-14 dioxide absorbed by plant life– Animal life eats the plant life, absorbs C-14– Steady state evolves … until object dies– After death, the decay rate reduces C-14

14C is continually produced in the atmosphere and incorporated into life cycles, so 14C amount in living things is constant. Upon

death, no more 14C is absorbed, so concentration decreases. Measuring the remaining radioactivity provides an age estimate.

The half life of 14C is 5730 years. The method is good for

estimating age of objects 500 to 50,000 years old.

Decay of Carbon-14Neutron turns into proton + electron (beta particle)Mass remains at 14, but carbon becomes nitrogen

Quark model useful to illustrate charges

Half Life calculations• Reduction in material is non-linear• original½ at half-life¼ at 2 half-

lives• General equation: • n1/n0 = (0.5)^(#of half lives)

– n1/n0 = (0.5)^1 50% remaining– n1/n0 = (0.5)^2 25% remaining– n1/n0 = (0.5)^3 12.5% remaining

Half Life calculations• Carbon dating example: (reverse example)

– old object has 12.79% normal C14

– Half life of C14 is 5730 years

• n1/n0 = (0.5)^(number of half lives)– Take natural logs to eliminate exponents:

• Ln(n1/n0)= Ln(0.5)*(t / 5730)• Ln(0.1279/1.00)= Ln(0.5)*(t / 5730)

– Ln(0.1279)= -.6931(t / 5730)– -2.0565 = -0.6931 * (t / 5730)– t = (-2.0565)*(5730 years)/-0.69314 = 17,002 years

56

Radioisotopes used internally for medical applications have short half-lives so that they decay rapidly and do not remain in the body for prolonged periods.

57

11.6 Radioactive Decay Series• Decay series: A

series of nuclear disintegrations leading from a heavy radioisotope to a nonradioactive product.

• Uranium-238, for example, undergoes a series of 14 sequential nuclear reactions, ultimately stopping at lead-206.

URANIUM-238 DECAY SERIESRadioactive Atomic Nuclear Radioactive Decay Particle EnergyElement Number Mass Half Life Mode Ejected MeV Comments---------------- ---------- ---------- -------------------- --------- ----------- --------- ----------------------------------------------Uranium 92 238 4.46 BillionYears Alpha 2He4

4.2 99.283% natural Uranium is 238

Thorium 90 234 24 days Beta electron 0.3

Proactinium 91 234 1.18 minutes Beta electron Uranium 92 234 247K years Alpha 2He4

4.8 0.0054% natural Uranium is 234

Thorium 90 230 80K years Alpha 2He44.7

Radium 88 226 1.6K years Alpha 2He44.8 Equilib@1Ra232 per 2.8M-U238

Radon 86 222 3.82 days Alpha 2He45.5 Gaseous health hazard

Note: Multiple disintegration paths exist, this is majority path, minority paths listed below also end at Pb-206Polonium 84 218 3.05 minutes Alpha 2He4

6.0 99.98% path

Lead 82 214 26.8 minutes Beta electron 1.0 99.98% path

Bismuth 83 214 19.7 minutes Beta electron 1.5 99.96% pathPolonium 84 214 0.164 millisec Alpha 2He4

7.7 99.96% path

Lead 82 210 21 year Beta electron 0.1 common intermediate step

Bismuth 83 210 5 days Beta electron 1.2 99.9998% pathPolonium 84 210 138 days Alpha 2He4

5.3 used in Ionizers, 99.9998%path

Lead 82 206 STABLE

Note: U-235 (Actinide series) is 0.7110% of natural Uranium, Total U-234+235+238=99.9994%

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11.7 Ionizing Radiation• A large dose of ionizing radiation can destroy living cells,

causing death. • A small dose of ionizing radiation may not cause visible

symptoms but might lead to a genetic mutation or cancer.

Radiation Intensity

60

• Health professionals who work with X rays or other kinds of ionizing radiation protect themselves by surrounding the source with a thick layer of lead or other dense material.

• Protection is also afforded by controlling the distance between the worker and the radiation source because radiation intensity (I) decreases with the square of the distance from the source. We will demonstrate inverse square law this week in lab.

• The intensities (I) of radiation at two different distances (d) are given by the equation:

I1d12 = I2d2

2

Inverse Square Example

• Radiation intensity is 2250 at 2 meters, what is intensity at 3 meters?

• I1 * d12 = I2 * d2

2

• 2250 * 22 = I2 * 32

• I2 = 2250*4/9 = 1000

• Moving away by 1 meter cuts radiation by more than half

Inverse Square Law

Inverse square law

• Intensity of radiation falls with distance

• A non-linear relationship– Twice as far ¼ the intensity– Works with all forms of point source radiation– Why planet Mercury is so hot, Venus so cold

Chain Reaction• Postulated in 1930’s

– Fission induces more fission, an avalanche– “critical mass” required to sustain reaction– Only certain isotopes sustain the reaction

• Uranium 235 and Plutonium 239 most common• Show You-Tube simulation

• First atomic reactor University of Chicago– Concentrated U235 required– The critical mass for lower-grade uranium depends

strongly on the grade: – 20% U235 requires over 400 kg– 15% U235 requires over 600 kg.

Critical Mass

• A chain reaction requires a minimum amount of material for to be self sustaining

U235 %

• Natural 0.711% U235 cannot sustain a chain reaction. Too much distance & shielding between fissionable atoms.

• Minimal enrichment OK for reactors

• High enrichment for weapons, reduces minimum mass and increases reaction rate.

The “Calutron” Initial method for separating U235 from U238 in 1942,

providing material used in the Hiroshima bomb.A type of mass spectrometer, but slow and expensive multiple

units built in Berkeley and Oak Ridge but gaseous diffusion eventually proved a more practical method

First Nuclear Fission Bomb

Atomic Bomb ExplosionAutomatic Camera situated 7 miles from blast with 10 foot lens. Shutter speed

1/100,000,000 second. Joshua tree’s near base vaporized in microseconds.

Nuclear Fusion

• Nuclear fusion: The joining together of light nuclei.

• Light nuclei such as the isotopes of hydrogen release enormous amounts of energy when they undergo fusion. It is fusion reactions of hydrogen nuclei to produce helium that powers our sun and other stars.

• The necessary conditions for nuclear fusion are not easily created on earth.

• In stars the temperature is on the order of 2 x 107 K and pressures approach 1 x 105 atmospheres. At these extremes, nuclei are stripped of all their electrons and have enough kinetic energy that nuclear fusion readily occurs.

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Fusion is primary energy source

• Universe mostly Hydrogen– Hydrogen fuses at high temperature to Helium

• Helium mass less that Hydrogen starting material• Balance of mass converted to energy• Fusion reaction powers the sun• Sun is a continuously operating Hydrogen bomb

– Sun is also our primary light source• Fundamental basis for life on earth• Numerous energy conversion processes

Nuclear Fusion in the Sun

Nuclear FusionPrinciple source of energy in stars from fusing hydrogen

atom of helium weighs slightly less than 4 hydrogen, balance is energy

Heavier elements formed in starsformation due extreme temperatures & pressures inside star

Nuclear Fusion (Hydrogen) Bomb

Medical Issues

• Radiation poisoning– Bad if uncontrolled fallout (Chernobyl)– Good if controlled attack on tumors– Similar idea for chemotherapy

• Radiation protection– Radioactive iodine from nuclear accidents– Thyroid collects & concentrates iodine– Use of potassium iodide to saturate thyroid

prevents uptake of radioactive fallout iodine

Thyroid Cancer

Chernoblefallout victims

Chernobyl reactor meltdown2.3% radiation increase world-wide

Now to our Experiment• Radiation versus distance

– Demonstrate inverse square law

• Use of shielding– Protection depends on mass

• Half-Life– Observing a half life of 153 seconds.

• Common Objects– Radioactive items are all around you

• Personal exposure Estimate– Radon, cosmic rays, medical procedures

Inverse Square Law

• You will see effect of distance on exposure– Good idea to be far away from sources

• Influence is non-linear– Double the distance 1/4 the exposure– Triple the distance 1/9 the exposure– Ten times distance 1/100 the exposure

Shielding

• Shielding depends on radiation type– α (helium nucleus) energetic, low penetration– Β (electron) less energy, modest penetration– Γ (x-ray) low energy, highly penetrating

• Shielding also depends on shield material– Higher density works better

• Will evaluate multiple shields and sources

Household Objects

• How radioactive are common items?– Pottery– Minerals– Glassware– Salt substitute (potassium chloride)– Brazil nuts

Half Life Demonstration

• Directly study a very short half-life

Personal radiation exposure

• Add up your personal exposure

Los Alamos National Laboratory's Periodic Table

Group**

Period 1 IA 1A

18

VIIIA 8A

1 1 H

1.008

2

IIA 2A

13

IIIA 3A

14

IVA 4A

15

VA 5A

16

VIA 6A

17

VIIA 7A

2 He 4.003

2 3

Li 6.941

4 Be 9.012

5 B

10.81

6 C

12.01

7 N

14.01

8 O

16.00

9 F

19.00

10 Ne 20.18

8 9 10

3 11

Na 22.99

12 Mg 24.31

3

IIIB 3B

4

IVB 4B

5

VB 5B

6

VIB 6B

7

VIIB 7B

------- VIII -------

------- 8 -------

11

IB 1B

12

IIB 2B

13 Al 26.98

14 Si

28.09

15 P

30.97

16 S

32.07

17 Cl

35.45

18 Ar 39.95

4 19 K

39.10

20 Ca 40.08

21 Sc 44.96

22 Ti

47.88

23 V

50.94

24 Cr 52.00

25 Mn 54.94

26 Fe 55.85

27 Co 58.47

28 Ni 58.69

29 Cu 63.55

30 Zn 65.39

31 Ga 69.72

32 Ge 72.59

33 As 74.92

34 Se 78.96

35 Br 79.90

36 Kr 83.80

5 37

Rb 85.47

38 Sr

87.62

39 Y

88.91

40 Zr

91.22

41 Nb 92.91

42 Mo 95.94

43 Tc (98)

44 Ru 101.1

45 Rh 102.9

46 Pd 106.4

47 Ag 107.9

48 Cd 112.4

49 In

114.8

50 Sn 118.7

51 Sb 121.8

52 Te 127.6

53 I

126.9

54 Xe 131.3

6 55

Cs 132.9

56 Ba 137.3

57 La* 138.9

72 Hf 178.5

73 Ta 180.9

74 W

183.9

75 Re 186.2

76 Os 190.2

77 Ir

190.2

78 Pt

195.1

79 Au 197.0

80 Hg 200.5

81 Tl

204.4

82 Pb 207.2

83 Bi

209.0

84 Po (210)

85 At (210)

86 Rn (222)

7 87 Fr

(223)

88 Ra (226)

89 Ac~ (227)

104 Rf (257)

105 Db (260)

106 Sg (263)

107 Bh (262)

108 Hs (265)

109 Mt (266)

110 ---

()

111 ---

()

112 ---

()

114 ---

()

116 ---

()

118 ---

()

Lanthanide Series*

58 Ce 140.1

59 Pr

140.9

60 Nd 144.2

61 Pm (147)

62 Sm 150.4

63 Eu 152.0

64 Gd 157.3

65 Tb 158.9

66 Dy 162.5

67 Ho 164.9

68 Er

167.3

69 Tm 168.9

70 Yb 173.0

71 Lu 175.0

Alpha ParticleUnstable element disintegrates, emitting a helium nuclei in the process. Numerators and denominators must banance

for both charge and mass