Atomic Mass: Atomic mass refers to the mass of an individual atom of an element. It is typically expressed in atomic mass units (amu) or unified atomic mass units (u). The atomic mass represents the total mass of protons, neutrons, and electrons in the atom. Since electrons have a much smaller mass compared to protons and neutrons, they are often neglected when calculating atomic mass.
The atomic mass of an element is determined by the number of protons and neutrons in the atom's nucleus. Protons and neutrons contribute almost equally to the atomic mass. The atomic mass of an element is usually listed on the periodic table, and it can be an average value due to the presence of different isotopes of the element.
Relative Atomic Mass: Relative atomic mass, also known as atomic weight, is the average mass of all the naturally occurring isotopes of an element, taking into account their abundance. Since many elements have multiple isotopes with different masses, the relative atomic mass provides an average value that reflects the isotopic composition of the element found in nature.
The relative atomic mass is calculated by considering the mass of each isotope and its relative abundance. The masses are weighted according to the proportion of each isotope present in a given sample of the element. The relative atomic mass is dimensionless and is often represented as a ratio with the value of 12 assigned to the isotope carbon-12 as a reference.
It's important to note that the terms "atomic mass" and "relative atomic mass" are sometimes used interchangeably, but the context usually clarifies their specific meanings.