1. Bellringer 10/01/12 How many protons, neutrons and electrons are in U-235 and Pu-244?

2. IsotopeSymbolComposition of the nucleus Isotope Mass in (amu) Relative Abundance (% in nature) Copper-63 63 29 29 protons 34 neutrons 62.9369.2 % Copper-65 65 29 29 protons 36 neutrons 64.9330.8 % Calculating Average Mass Atomic mass is the average of all the naturally isotopes of that element. Copper = 63.546 amu Cu xMass (amu)Relative abundance (% as a decimal) x62.93 amu0.692= 43.54756 amu Copper-63 Copper-65 x64.93 amu0.308= 19.99844 amu + 63.546 amu Periodic Table of Elements

3. IsotopeSym bol Atomic # neutronselectronsMass Number (p + + n 0 ) Isotope Mass in (amu) Relative abundance Carbon-12 6C6C 612 - 6 = 66 -6 + 6 = 1212.00098.89% Carbon-13 6C6C 613 – 6 = 76 -6 + 7 = 1313.0031.11% Your Turn (Calculate Average Mass) 12 13 C Carbon 6 12.011 Atomic # Atomic mass (average) xMass (amu)Relative abundance (% as a decimal) x12.000 amu0.9889= 11.8668 amu Carbon-12 Carbon-13 x13.003 amu0.0111= 0.1443333 amu + 12.0111333 amu12.01 amu

4. IsotopeSym bol Atomic # neutronselectronsMass Number (p + + n 0 ) Isotope Mass in (amu) Relative abundance Nitrogen-14 N 14.00399.63% Nitrogen-15 N 15.0000.37% Chlorine-35 Cl 34.96975.77% Chlorine-37 Cl 36.96624.23% 14 7 7 14-7=7 7-14 15 7 7 15-7=8 7-15 35 17 35-17=18 17-35 37 17 37-17=20 17-37 xMass (amu)Relative abundance (% as a decimal) x14.003 amu0.9963= 13.9511889 amu Nitrogen-14 Nitrogen-15 x15.000 amu0.0037 + 14.0066889 amu 14.007 amu = 0.0555 amu N Nitrogen 7 14.007 Your Turn (Calculate Average Mass)

5. IsotopeSym bol Atomic # neutronselectronsMass Number (p + + n 0 ) Isotope Mass in (amu) Relative abundance Nitrogen-14 N 14.00399.63% Nitrogen-15 N 15.0000.37% Chlorine-35 Cl 34.96975.77% Chlorine-37 Cl 36.96624.23% 14 7 7 14-7=7 7-14 15 7 7 15-7=8 7-15 35 17 35-17=18 17-35 37 17 37-17=20 17-37 xMass (amu)Relative abundance (% as a decimal) x34.969 amu0.7577= 26.4960113 amu Chlorine-35 Chlorine-37 x36.966 amu0.2423 + 35.4528731 amu 35.453 amu = 8.9568618 amu Cl Chlorine 17 35.453 Your Turn (Calculate Average Mass)

6. Mass # = p + + n 0 Calculate Average Mass xMass (amu)Relative abundance (% as a decimal) x2040.0137= 2.7948 Lead-204 Lead-206 x2060.2626 + 207.2118 207.21 = 54.0956 Pb Lead 82 207.20 82p 122n 82p 124n 82p 125n 82p 126n 1.37% 26.26%20.82%51.55% Mass # 204 206 207 208 No amu mass shown. Use mass # instead. % abundance: Lead-207 x2070.2082 = 43.0974 Lead-208 x2080.5155 = 107.224 1.37 100

7. IsotopeSym bol Atomic # neutronselectronsMass Number (p + + n 0 ) Isotope Mass in (amu) Relative abundance Helium-3 2 He 212 -33.01600.0001% Helium-4 2 He 222 -44.002699.9999% Your Turn (Calculate Average Mass) 3 4 He Helium 2 4.0026 Atomic # Atomic mass (average) xMass (amu)Relative abundance (% as a decimal) x3.0160 amu0.000001= 0.000003016 amu Helium-3 Helium-4 x4.0026 amu0.999999= 4.002595997 amu + 4.002599013 amu 4.0026 amu