Final answer:
The atomic mass of an element is the average mass of all its isotopes, while the mass number refers to the sum of the protons and neutrons in an atom's nucleus. Atomic mass is a weighted average, while mass number is specific to each isotope. An example is carbon, which has an atomic mass of 12.01 g/mol and three isotopes with mass numbers 12, 13, and 14.
Step-by-step explanation:
In chemistry, the atomic mass of an element refers to the average mass of all the isotopes of that element, taking into account their relative abundances. It is a weighted average based on the isotopic mass and the abundance of each isotope. The atomic mass is usually represented as a decimal number on the periodic table.
On the other hand, the mass number of an element refers to the sum of the number of protons and neutrons in the nucleus of an atom of that element. It is always a whole number and is represented by the top left corner of the element's symbol on the periodic table. The mass number is specific to each isotope of an element.
For example, let's take the element carbon. Carbon has three naturally occurring isotopes: carbon-12, carbon-13, and carbon-14. The atomic mass of carbon is approximately 12.01 g/mol, which is a weighted average of the isotopic masses and their abundances. The mass number for carbon-12 is 12, for carbon-13 is 13, and for carbon-14 is 14.
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