One isotope of carbon (C) has exactly the same mass number and atomic mass since it was used as the definition of the atomic mass unit (amu). Which isotope is it and what is its atomic mass?

An isotope of a chemical element is an atom that has a different mass number but the same atomic number as the element. The difference in mass number is from the number of neutrons (that is, a greater or lesser atomic mass) than the standard for that element.

Carbon-12 is an isotope of carbon it has 6 neutrons and 6 protons, giving it a mass number of 12 and atomic number of 6. Carbon-12 is a stable isotope of carbon, it has the same mass number and atomic number as carbon.

AFOKE88 AFOKE88 · Answer 2 · 2021-10-08T19:32:36+02:00

The isotope of carbon that has exactly the same mass and atomic number as used in the definition of the atomic mass unit is;

Isotope Carbon-12.

In chemistry, we know that;

Mass number is defined as the sum of the protons and the neutrons present in the nucleus of an atom.

Meanwhile, Atomic number is defined the number of protons in the nucleus or number of electrons around the nucleus of an atom.

While an isotope is defined as an atom of an element that has the same atomic number but different mass number.

The isotope Carbon-12 is an isotope of carbon that has 6 protons and 6 neutrons.

This means from the definition of mass number; Carbon-12 will have a mass number = 6 + 6 = 12

Number of protons = number of electrons. Thus, number of electrons = 6 and therefore, atomic number = 6.

From periodic table, the element Carbon has the same mass number and atomic number as its' isotope carbon-12.

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