Matching the Content to Your Class (I was told there would be no math)

Matching the Content Matching the Content to Your Classto Your Class

(I was told there would be (I was told there would be no mathno math))

Atoms and IsotopesAtoms and IsotopesWhat are atoms, isotopes, and What are atoms, isotopes, and

radioactive decay?radioactive decay?

The Harnessed Atom 3Atoms and Isotopes

Today’s TopicsToday’s Topics

How is energy stored in an atom?How is energy stored in an atom? Atoms and subatomic particlesAtoms and subatomic particles

Elements (Periodic Table)Elements (Periodic Table)

Isotopes (Chart of Nuclides)Isotopes (Chart of Nuclides)

Nuclear forces, stability, and binding Nuclear forces, stability, and binding energyenergy

Radioactive decayRadioactive decay


Atoms and Subatomic ParticlesAtoms and Subatomic Particles

Atoms are Atoms are the smallest unit of a the smallest unit of a chemical element that has all the chemical element that has all the chemical properties of that elementchemical properties of that element. .

Made up of:Made up of: Protons– positive chargeProtons– positive charge Neutrons—no chargeNeutrons—no charge Electrons—negative chargeElectrons—negative charge


The Periodic Table of the The Periodic Table of the ElementsElements

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

Actinide Series~ 90

Th 232.0

91 Pa (231)

92 U

(238)

93 Np (237)

94 Pu (242)

95 Am (243)

96 Cm (247)

97 Bk (247)

98 Cf (249)

99 Es (254)

100 Fm (253)

101 Md (256)

102 No (254)

103 Lr (257)


Reading Atomic NotationsReading Atomic Notations

Z is the atomic (proton) number Z is the atomic (proton) number N is the neutron numberN is the neutron number A is the mass number (N+Z)A is the mass number (N+Z) X is the chemical element symbolX is the chemical element symbol

A Z XN


IsotopesIsotopes Atoms of one element may have different Atoms of one element may have different

number of neutrons: the different possible number of neutrons: the different possible versions of each element are called isotopes.versions of each element are called isotopes.

Isotopes of one element all have the same Isotopes of one element all have the same number of protons (atomic number, Z) but number of protons (atomic number, Z) but different numbers of neutrons (thus different different numbers of neutrons (thus different atomic weights, A). atomic weights, A).

Every element has several isotopesEvery element has several isotopes All isotopes are shown on the chart of the nuclides.All isotopes are shown on the chart of the nuclides.


Isotopes of the element sodium– 11 protons

Isotopes of the element oxygen–

8 protons


Nuclear ForcesNuclear Forces

Weak Nuclear ForcesWeak Nuclear Forces Particles with like charges repel.Particles with like charges repel.

This causes electrons to orbit around the This causes electrons to orbit around the nucleus.nucleus.



Strong Nuclear ForcesStrong Nuclear Forces Particles in the nucleus actually are held Particles in the nucleus actually are held

together by an even stronger attractive together by an even stronger attractive force.force.

Acts only at very short distances (about Acts only at very short distances (about 1010-15-15m)—beyond this distance, the strong m)—beyond this distance, the strong nuclear force is negligible. nuclear force is negligible.



Two protons more than Two protons more than 1010-15-15m will repel each m will repel each other by their like other by their like charges.charges.

Inside a nucleus, the Inside a nucleus, the distances are small distances are small enough that the enough that the strong strong nuclear forcenuclear force overcomes the overcomes the weak weak repulsive force,repulsive force, holding holding the protons and neutrons the protons and neutrons together. together.



Big Idea of Science:Big Idea of Science:There are only fourThere are only fourknown forces in nature:known forces in nature:

1.1. GravityGravity

2.2. ElectromagnetismElectromagnetism

3.3. Weak Nuclear ForceWeak Nuclear Force

4.4. Strong Nuclear ForceStrong Nuclear Force


Think about it…Think about it…

How might a higher number of neutrons How might a higher number of neutrons change the balance between the change the balance between the repulsive and attractive forces in a repulsive and attractive forces in a nucleus? nucleus?

How might a lower number of neutrons How might a lower number of neutrons affect this same balance?affect this same balance?


Nuclear StabilityNuclear Stability

The stability of an atom is the balance The stability of an atom is the balance of the repulsive and attractive forces of the repulsive and attractive forces within the nucleus (strong and weak within the nucleus (strong and weak force in equilibrium).force in equilibrium).



If the attractive strong forces If the attractive strong forces prevail, the nucleus is stable. prevail, the nucleus is stable.

If the repulsive weak forces If the repulsive weak forces outweigh the attraction of the strong outweigh the attraction of the strong forces, the nucleus is unstable.forces, the nucleus is unstable.



For elements with low atomic numbers, For elements with low atomic numbers, atoms are stable when their neutron to atoms are stable when their neutron to proton ratio is close to one (1:1). proton ratio is close to one (1:1).

As atomic number increases, stable atoms As atomic number increases, stable atoms have ratios greater than one (1:1.5). have ratios greater than one (1:1.5).

This is because at higher atomic numbers, This is because at higher atomic numbers, more neutrons are needed to counteract more neutrons are needed to counteract the repulsive forces between the protons. the repulsive forces between the protons.


Nuclear StabilityNuclear Stability The shaded cluster is The shaded cluster is

the “band of stability.” the “band of stability.” The solid line The solid line

represents a neutron-represents a neutron-to-proton ratio of 1:1. to-proton ratio of 1:1.

Nuclei to the right of the Nuclei to the right of the band of stability don’t band of stability don’t have enough neutrons have enough neutrons to remain stable.to remain stable.

Nuclei to the left of the Nuclei to the left of the band have too many band have too many neutrons to remain neutrons to remain stable.stable.


Nuclear Binding EnergyNuclear Binding Energy

The energy stored in the bonds within an atomThe energy stored in the bonds within an atom Released when an atom breaks apartReleased when an atom breaks apart Represented by the equation:Represented by the equation:

EEbb (MeV) = ( (MeV) = (ZmZmpp + + NmNmnn – M – MAA) x 931.494 MeV/amu) x 931.494 MeV/amu

Where:Where: 1 amu1 amu = 1.66 x 10-24 grams = 1.66 x 10-24 grams [amu = atomic mass unit][amu = atomic mass unit] EEbb= binding energy= binding energy Zm= mass of the protons in amuZm= mass of the protons in amu Nm= mass of neutronsNm= mass of neutrons MMAA= = mass of the atommass of the atom MeV= millions of electron volts, a unit of measure used to MeV= millions of electron volts, a unit of measure used to

represent the energy in nuclear equationsrepresent the energy in nuclear equations


Radioactive DecayRadioactive Decay

Unstable atoms will spontaneously Unstable atoms will spontaneously transform until they reach a stable transform until they reach a stable configuration. configuration.

These transformations are accompanied These transformations are accompanied by releases of energy. by releases of energy.



This energy, given off in waves from an This energy, given off in waves from an atom, is known as atom, is known as radiationradiation. . Substances that give off radiation are called Substances that give off radiation are called

radioactive.radioactive. The process of isotopes emitting particles and The process of isotopes emitting particles and

energy to become more stable is called energy to become more stable is called radioactive decayradioactive decay..



Main types of radioactive decay:Main types of radioactive decay: Alpha emissionAlpha emission Beta emissionBeta emission Positron emissionPositron emission Gamma emissionGamma emission



Alpha emission (Alpha emission (αα)) Nucleus emits an alpha particle—two protons

and two neutrons Equivalent to a helium nucleus (He).

Alpha Decay Animation http://ie.lbl.gov/education/glossary/AnimatedDecays/AlphaDecay.html

238 92U 234

90Th + 4 2 He

http://ie.lbl.gov/education/glossary/AnimatedDecays/AlphaDecay.html



Beta Emission (Beta Emission (ββ)) Nucleus emits an electron, and a Nucleus emits an electron, and a

neutron is converted to a proton.neutron is converted to a proton.

Beta Decay Animations: Beta Decay Animations: http://ie.lbl.gov/education/glossary/AnimatedDecays/Beta-Decay.htmlhttp://ie.lbl.gov/education/glossary/AnimatedDecays/Beta-Decay.html

131 53I 131

54Xe + 0 -1 e

http://ie.lbl.gov/education/glossary/AnimatedDecays/Beta-Decay.html



Positron EmissionPositron Emission Nucleus emits a Nucleus emits a

positron (identical to positron (identical to an electron in mass, an electron in mass, but has a positive but has a positive charge)charge)

Positron is formed Positron is formed when a proton when a proton converts to a neutron. converts to a neutron.

11 6 C 11

5 B + 0 1 e



Gamma emission (Gamma emission (γγ)) Nuclei seeking lower energy states Nuclei seeking lower energy states

emit electromagnetic radiation, which emit electromagnetic radiation, which is in the gamma ray region of the is in the gamma ray region of the electromagnetic spectrum.electromagnetic spectrum.

Rays are emitted in conjunction with Rays are emitted in conjunction with another type of decay (alpha or beta).another type of decay (alpha or beta).

Gamma Decay Gamma Decay http://ie.lbl.gov/education/glossary/AnimatedDecays/GammaDecay.htmlhttp://ie.lbl.gov/education/glossary/AnimatedDecays/GammaDecay.htmlAdditional animations: Additional animations: http://http://ie.lbl.gov/education/glossary/Glossary.htmie.lbl.gov/education/glossary/Glossary.htm

http://ie.lbl.gov/education/glossary/AnimatedDecays/GammaDecay.html

http://ie.lbl.gov/education/glossary/Glossary.htm

http://ie.lbl.gov/education/glossary/Glossary.htm


Radioactive Decay ChainsRadioactive Decay Chains


Half LifeHalf Life

The amount of time it takes for half The amount of time it takes for half of the atoms of a given isotope to of the atoms of a given isotope to decay to another form is known as decay to another form is known as its half-life. its half-life.

The value can be from fractions of The value can be from fractions of a second to billions of years. a second to billions of years.


Half LifeHalf Life Half-life values are constant. Half-life values are constant. There is no way to speed up or slow There is no way to speed up or slow

down this natural process.down this natural process. CannotCannot predict when a specific atom predict when a specific atom

will decay.will decay. CanCan predict the number of atoms that predict the number of atoms that

will decay in a certain time period.will decay in a certain time period.


Half Life of Uranium-235Half Life of Uranium-235


Words to Know…Words to Know… Alpha decayAlpha decay AtomAtom Beta decayBeta decay Chart of Chart of

NuclidesNuclides Coulomb’s forceCoulomb’s force ElectronElectron Electron captureElectron capture ElementElement Gamma decayGamma decay Half-LifeHalf-Life IsotopeIsotope

NeutronNeutron Nuclear forceNuclear force NucleusNucleus NuclideNuclide Periodic TablePeriodic Table PositronPositron ProtonProton RadiationRadiation Radioactive DecayRadioactive Decay Stability Stability

The Ah Ha! MomentThe Ah Ha! Moment

Interdisciplinary ContentInterdisciplinary Content

Fact, Opinion, Bias, and Critical Fact, Opinion, Bias, and Critical ThinkingThinking

Tell Us How You Teach ThisTell Us How You Teach This

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