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

radioactive decay?radioactive decay?

The Harnessed Atom 2Atoms and Isotopes

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 Harnessed Atom 3Atoms and Isotopes

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)

The Harnessed Atom 4Atoms and Isotopes

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

The Harnessed Atom 5Atoms and Isotopes

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.

The Harnessed Atom 6Atoms and Isotopes

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.

The Harnessed Atom 7Atoms and Isotopes

Radioactive DecayRadioactive Decay 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..

The Harnessed Atom 8Atoms and Isotopes

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

The Harnessed Atom 9Atoms and Isotopes

Radioactive DecayRadioactive DecayAlpha 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

The Harnessed Atom 10Atoms and Isotopes

Radioactive DecayRadioactive DecayBeta 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 53 I 131

54Xe + 0 -1 e

The Harnessed Atom 11Atoms and Isotopes

Radioactive DecayRadioactive DecayPositron 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

The Harnessed Atom 12Atoms and Isotopes

Radioactive DecayRadioactive DecayGamma 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

The Harnessed Atom 13Atoms and Isotopes

Radioactive Decay ChainsRadioactive Decay Chains

The Harnessed Atom 14Atoms and Isotopes

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.

The Harnessed Atom 15Atoms and Isotopes

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.

The Harnessed Atom 16Atoms and Isotopes

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