GK
NUCLEAR SCIENCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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As an average of the mass of different isotopes
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As the exact mass of every atom
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As the mass of the most common isotope
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As the masses of all the protons added together
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Detailed explanation-1: -Average atomic mass = f1M1 + f2M2 +… + fnMnwhere f is the fraction representing the natural abundance of the isotope and M is the mass number (weight) of the isotope. The average atomic mass of an element can be found on the periodic table, typically under the elemental symbol.
Detailed explanation-2: -Atomic Mass and Mass Number The difference is that atomic mass on the periodic table is the average mass of all the isotopes of a naturally-occurring sample of an element. In contrast, the mass number is the number of protons and neutrons of a single atom of an element.
Detailed explanation-3: -Different isotopes of an element have the same number of protons in the nucleus, giving them the same atomic number, but a different number of neutrons giving each elemental isotope a different atomic weight.
Detailed explanation-4: -The mass written on the periodic table is an average atomic mass taken from all known isotopes of an element. This average is a weighted average, meaning the isotope’s relative abundance changes its impact on the final average. The reason this is done is because there is no set mass for an element.
Detailed explanation-5: -The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance value. Natural abundance is the decimal related to the percent of atoms of that element which is of given isotope.