Question

ssessment. 1. the element lead has four known isotopes. using the formula percentage of abundance times mass calculate the correct masses based on their percentages. then add all four together to match the average atomic mass of the element as it appears on the periodic table of elements. a. lead 204: 1.4% 203.973 answer: ______ b. lead 206: 24.10% 205.974 c. lead 207 : 22.10% 206.976 d. lead 208: 52.40% 207.977

Explanation:

Step1: Calculate contribution of Lead 204

Convert percentage to decimal: \(1.4\% = 0.014\). Multiply by mass: \(0.014\times203.973\)
\(0.014\times203.973 = 2.855622\)

Step2: Calculate contribution of Lead 206

Convert percentage to decimal: \(24.10\% = 0.241\). Multiply by mass: \(0.241\times205.974\)
\(0.241\times205.974 = 49.639734\)

Step3: Calculate contribution of Lead 207

Convert percentage to decimal: \(22.10\% = 0.221\). Multiply by mass: \(0.221\times206.976\)
\(0.221\times206.976 = 45.741696\)

Step4: Calculate contribution of Lead 208

Convert percentage to decimal: \(52.40\% = 0.524\). Multiply by mass: \(0.524\times207.977\)
\(0.524\times207.977 = 108.980948\)

Step5: Sum all contributions

Add the four results: \(2.855622 + 49.639734 + 45.741696 + 108.980948\)
\(2.855622+49.639734 = 52.495356\); \(52.495356 + 45.741696 = 98.237052\); \(98.237052 + 108.980948 = 207.218\) (rounded to three decimal places)

Answer:

The average atomic mass of lead is approximately \(207.218\)