Isotope Symbol Composition of the nucleus

IsotopeMass in(amu)

Relative Abundance

(% in nature)

Copper-63

63

29

29 protons34 neutrons 62.93 69.2 %

Copper-65

65 29

29 protons36 neutrons 64.93 30.8 %

Calculating Average Calculating Average MassMassAtomic mass is the average of all the

naturally isotopes of that element.Copper = 63.546 amu

Cu

Cu

xMass (amu) Relative abundance (% as a decimal)

x62.93 amu 0.692 = 43.54756 amu Copper-63

Copper-65 x64.93 amu 0.308 = 19.99844 amu +63.546 amu

Periodic Table of Elements

Isotope Symbol

Atomic #

neutrons

electrons

Mass Number

(p+ + n0)

Isotope Mass

in (amu)

Relative abundan

ce

Carbon-12 6C6 12 - 6

= 66 - 6 + 6 =

1212.000 98.89%

Carbon-13 6C6 13 – 6

= 76 - 6 + 7 =

1313.003 1.11%

Your Turn (Calculate Average Your Turn (Calculate Average Mass)Mass)

12

13

CCarbon

6

12.011

Atomic #

Atomic mass(average)

xMass (amu) Relative abundance (% as a decimal)

x12.000 amu 0.9889 = 11.8668 amu Carbon-12

Carbon-13 x13.003 amu 0.0111 = 0.1443333 amu +12.0111333 amu12.01 amu

Isotope Symbol

Atomic #

neutrons

electrons

Mass Number

(p+ + n0)

Isotope Mass

in (amu)

Relative abundan

ce

Nitrogen-14 N 14.003 99.63%

Nitrogen-15 N 15.000 0.37%

Chlorine-35 Cl 34.969 75.77%

Chlorine-37 Cl 36.966 24.23%

14

77 14-7=7 7- 14

15

7 7 15-7=8 7- 15

35

1717 35-17=18 17- 35

37

1717 37-17=20 17- 37

xMass (amu) Relative abundance (% as a decimal)

x14.003 amu 0.9963 = 13.9511889 amu Nitrogen-14

Nitrogen-15 x15.000 amu 0.0037 +14.0066889 amu

14.007 amu

= 0.0555 amu

NNitrogen

7

14.007

Your Turn (Calculate Average Your Turn (Calculate Average Mass)Mass)

Isotope Symbol

Atomic #

neutrons

electrons

Mass Number

(p+ + n0)

Isotope Mass

in (amu)

Relative abundan

ce

Nitrogen-14 N 14.003 99.63%

Nitrogen-15 N 15.000 0.37%

Chlorine-35 Cl 34.969 75.77%

Chlorine-37 Cl 36.966 24.23%

14

77 14-7=7 7- 14

15

7 7 15-7=8 7- 15

35

1717 35-17=18 17- 35

37

1717 37-17=20 17- 37

xMass (amu) Relative abundance (% as a decimal)

x34.969 amu 0.7577 = 26.4960113 amu Chlorine-35

Chlorine-37 x36.966 amu 0.2423 +35.4528731 amu

35.453 amu

= 8.9568618 amu

ClChlorine

17

35.453

Your Turn (Calculate Average Your Turn (Calculate Average Mass)Mass)

Mass # = p+ + n0

Calculate Average Mass

xMass (amu) Relative abundance (% as a decimal)

x204 0.0137 = 2.7948 Lead-204

Lead-206 x206 0.2626

+

207.2118

207.21

= 54.0956

PbLead

82

207.20

82p122n

82p124n

82p125n

82p126n

1.37% 26.26% 20.82% 51.55%

Mass # 204 206 207 208

No amu mass shown. Use mass # instead.

% abundance:

Lead-207 x207 0.2082 = 43.0974

Lead-208 x208 0.5155 = 107.224

1.37100

Isotope Symbol

Atomic #

neutrons

electrons

Mass Number

(p+ + n0)

Isotope Mass

in (amu)

Relative abundan

ce

Helium-3 2He 2 1 2 - 3 3.0160 0.0001%

Helium-4 2He 2 2 2 - 4 4.0026 99.9999%

Your Turn (Calculate Average Your Turn (Calculate Average Mass)Mass)

3

4

HeHelium

2

4.0026

Atomic #

Atomic mass(average)

xMass (amu) Relative abundance (% as a decimal)

x3.0160 amu 0.000001 = 0.000003016 amu Helium-3

Helium-4 x4.0026 amu 0.999999 = 4.002595997 amu +4.002599013 amu

4.0026 amu