Question

An element has two naturally occurring isotopes. Isotope 1 has a mass of 120.9038 amu and a relative abundance of 57.4%, and isotope 2 has a mass of 122.9042 amu and a relative abundance of 42.6%.

1.Find the atomic mass of this element

Express your answer using four significant figures.

2. By comparison to the periodic table, identify it.

Express your answer as a chemical symbol.

Answer 1

Solution :-

Isotope 1 = 120.9038 amu and it is 57.4%

Isotope 2 = 122.9042 amu and it is 42.6 %

Atomic mass of the abundance

1). Average atomic mass of the element is the sum of the atomic masses of the isotopes with respect to their percentages

Avg atomic mass = [ (120.9038 amu * 57.4 % / 100 %) +(122.9042 amu * 42.6 %/100%)]

                            = 121.8 amu

So the atomic mass of the element is 121.8 amu

2). The element in the periodic table having similar molar mass is antimony whose chemical symbol = Sb