Question

missed this? watch iwe 4.9; read section 4.9. you can click on the review link to access the section in your etext. an element has two naturally occurring isotopes. isotope 1 has a mass of 78.9183 amu and a relative abundance of 50.7%, and isotope 2 has a mass of 80.9163 amu and a relative abundance of 49.3%. part a find the atomic mass of this element. express your answer in atomic mass units to one decimal place. atomic mass = part b referring to the periodic table, identify it. express your answer as a chemical symbol.

Explanation:

Step1: Calculate the contribution of isotope 1

The contribution of isotope 1 is calculated by multiplying its mass by its relative abundance.

$$78.9183\times\frac{50.7}{100}=78.9183\times0.507 = 39.9115781$$

Step2: Calculate the contribution of isotope 2

The contribution of isotope 2 is calculated by multiplying its mass by its relative abundance.

$$80.9163\times\frac{49.3}{100}=80.9163\times0.493 = 39.9917359$$

Step3: Calculate the atomic mass

The atomic mass is the sum of the contributions of the two isotopes.

$$39.9115781 + 39.9917359=79.903314\approx79.9$$

Answer:

Atomic mass = \(79.9\)

For Part B, referring to the periodic table, the element with an atomic mass of approximately \(79.9\) amu is \(Br\) (bromine).