Oregon. A state of the northwest United States in the Pacific Northwest. It was admitted as the 33rd state in 1859. Claimed by the United States after Capt. Robert Gray explored the mouth of the Columbia River in 1792, the area was further explored by Lewis and Clark in 1805 and was soon the site of fur-trading posts.
The unified atomic mass unit (u) or Dalton ( Da) is a unit that is used for indicating mass on an atomic or molecular scale. One Da is approximately equal to the mass of one proton or one neutron. An atomic mass unit or amu is one twelfth of the mass of an unbound atom of carbon-12. This means that a carbon-12 atom has the atomic mass of 12 daltons. Mass is the property which reflects the quantity of matter within a sample.
Atomic mass. The atomic mass of an atom is the mass of that atom compared to some standard, such as the mass of a particular type of carbon atom. The terms atomic mass and atomic weight are often used interchangeably, although, strictly speaking, they do not mean the same thing. Mass is a measure of the total amount of matter in an object.