 |
| Atomic Mass Unit Scale |
|
| The scale in which the relative atomic masses of different atoms are expressed is called atomic mass unit scale. |
| |
| Modern definition of atomic mass unit |
| |
| The mass of 1/12 part of 12C
isotope of carbon is equivalent to one atomic mass unit. |
| |
|
| The atomic mass of an element is a
relative quantity and is the mass of one atom of the element relative to
1/12 the mass of one carbon-12 atom. Thus, |
| |
 |
| |
 |
| |
|
 |
| |
|
| The atomic mass of an element expressed in grams is called the gram atomic mass of an element. It is also called gram atom. |
| |
 |
| |
| Example: The gram atoms present in 46 grams of sodium |
| |
 |
| |
|
| Qualitative |
| |
 It represents a specific element. |
| |
 It represents one atom of an element. |
| |
| Quantitative |
| |
 It represents how many times an atom is heavier than one atomic mass unit. |
| |
 It represents one gram - atom of an element. |
| |
 It represents how many atoms are present in one gram atom (1 mole). |
| |
| For example, 12 grams of carbon has 6.023 x 1023 atoms in it. |
| |
