2suppose that a new element (e) were discovered that existed as three natural isotopes: 25% of atoms had a mass of 278, 38% had a mass of 281, and the remained had a mass of 285. what would be listed as the atomic mass of this element? explain your logic and show all steps.

Atomic mass of the element E is 281.73 amu.

Explanation: We are given an element E, having 3 isotopes.

Atomic mass of the element is calculated by:

.....(1)

Fractional abundance can be calculated by:

Mass of isotope 1 = 278 amu

Fractional abundance of isotope 1 = =0.25

Mass of isotope 2 = 281 amu

Fractional abundance of isotope 2 = 0.38

Mass of isotope 3 = 285 amu

Total fractional abundance = 1

Fractional abundance of isotope 3 = 1 - (0.25+0.38) = 0.37

Putting all the values in equation 1, we get

Atomic mass of the element E = 281.73 amu.

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o