The atomic mass of an element is the average relative mass of its atoms as compared with an atom of carbon 12 taken as 12.įractional abundance of an isotope is the fraction of the total number of atoms that is comprised of that particular isotope. The meaning of ATOMIC MASS UNIT is a unit of mass for expressing masses of atoms, molecules, or nuclear particles equal to 1/12 the mass of a single atom of.

One atomic mass unit is equal to one twelfth of the mass of an atom of carbon 12 isotope. Relative atomic mass average mass of an atom/mass of carbon-12 x (1/12) The average mass of an atom is calculated using the masses of different isotopes of an element and their abundance. Hence, the relative atomic mass of carbon-12 is 12 amu. Therefore carbon is taken reference for the determination of atomic masses.Ītomic mass of an element is the number of times an atom of that element is heavier than an atom of carbon taken as 12. One twelfth of the mass of an atom of carbon-12 is named as atomic mass unit (1 amu or 1 u). Expressing the weights of atoms or molecules was a problem for scientists in the early stages. One unified atomic mass unit can be quantified as the weight of one-twelfth of the mass of a carbon-12 atom considering that it is at rest. The atomic mass is used to find the average mass of elements and molecules and to solve stoichiometry problems. Initially, the atomic masses of all the elements were obtained by comparing with the mass of hydrogen taken as 1 but by doing so, the atomic masses of most of the elements came out to be fractional. The key difference between atomic mass unit and atomic mass is that the atomic mass unit is the unit that we use to measure the mass of an atom whereas the atomic mass is the mass of a particular single atom. Learn the basics about Atomic Mass Units. If the atomic mass of the hydrogen is taken is 1 ,the relative atomic mass of oxygen is 16. Thus, though the actual masses of the atoms could not be determined but their relative masses could be determined. If equal volumes of two different gases are taken under similar conditions of temperature and pressure and then weighted, the ratio of their masses will be equal to the ratio of their single molecules. The kilogram (SI unit symbol: kg) is the base unit of mass in the Metric system and is defined as being equal to the mass of the International Prototype of the Kilogram.more definition+ In relation to the base unit of mass weight > (kilograms), 1 Atomic Mass Unit (u) is equal to 1.660540199E-27 kilograms, while 1 Kilograms (kg) 1 kilograms. The problem was finally solved by Avogadro’s hypothesis.

The atomic mass unit is defined as 1/12 of the mass of the. 12 C is the most abundant natural carbon isotope, accounting for over 98 of carbon found in nature. AMU is defined as one-twelfth the mass of an atom of carbon-12 ( 12 C). As an atom is so small a particle that it cannot be seen or isolated ,therefore it is impossible to determine the actual mass of a single atom by weighing it. Atomic mass unit is a mass unit and is used to express the mass of atoms and other particles. Also known as the dalton (Da) or unified atomic mass unit (u), the AMU expresses both atomic masses and molecular masses.