Constants | Periodic Table Part A Most elements occur naturally as a mix of diff

Question

Constants | Periodic Table Part A Most elements occur naturally as a mix of different isotopes. An element's atomic mass is the weighted average of the isotope masses. In other words, it is an average that takes into account the percentage of each isotope. For example, the two naturally occurring isotopes of boron are given here What is the atomic mass of a hypothetical element that consists of the following isotopes in the indicated natural abundances? Isotopic mass Relative abundance sotope (amu) 76.9 78.9 79.9 13.2 14.7 72.1 sotope(amu) Isotopic mass Relative abundance 10 10.0 19.9 11.0 80.1 Express your answer to three significant figures and include the appropriate units The atomic mass of boron is calculated as follows: View Available Hint(s) (10.0 × 0.199) + (11.0 × 0.801) = 10.8 amu Because the heavier isotope is more abundant, the atomic mass is closer to 11 amu than it is to 10 ainu. Value amu SubmitPre Previous Answe

Explanation / Answer

Part-A

The atomic mass of an element =( 76.9x0.132) +( 78.9x0.147) +(79.9 x0.721)

                                                 = 10.1508 + 11.5983 +57.6079

                                                 = 79.357

The atomic mass of an element = 79.4 amu

Part-B

The atomic mass of an element = (57.93 x 0.6776) +(59.93 x0.2616) +(60.93 x 0.0125) + (61.93 x 0.0366) +(63.93 x0.0116)

The atomic mass = 39.253368 + 15.677688 +0.761625 + 2.266638 +0.741588

The atomic mass of an element = 58.7 amu

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