1.
a student looked up the naturally occurring isotopes of bromine and found the following information:
50.54% of the naturally occurring isotopes of bromine have an atomic mass of 78.92 amu while 49.46% of the
naturally occurring isotopes of bromine have an atomic mass of 80.92 amu. calculate the average atomic mass of
bromine. show all work

The average atomic mass of bromine is 79.91 amu.

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

  .....(1)

For isotope 1:

Mass of isotope 1 = 78.92 amu

Percentage abundance of isotope 1 = 50.54 %

Fractional abundance of isotope 1 = 0.5054

For isotope 2:

Mass of isotope 2 = 80.92 amu

Percentage abundance of isotope 2 = 49.46 %

Fractional abundance of isotope 2 = 0.4946

Putting values in equation 1, we get:

Hence, the average atomic mass of element bromine is 79.91 amu.

they are made of gases.

they have a spherical shape.

they make energy through fusion.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.