An element, Spencerecium, has two isotopes.  Spencerecium-145 has a relative abundance of 85 % and Spencerecium-140 has a relative abundance of 15 %.  What is the average atomic mass of Spencerecium?  Include two decimal places in your answer.

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Atoms and Molecules

An atom is the smallest unit of an element that possesses all the properties of that particular element. Molecules are the smallest unit of a substance that possess all the properties of that particular substance.