أرشيف الوسم : Atomic mass

ATOMS THREE POSTULATES OF DALTON’S ATOMIC THEORY 1) An element is composed of identical atoms. 2) Atoms of different elements have different properties. 3) Compounds are atoms of 2 or more elements chemically combined. THE LAW OF CONSERVATION OF MASS During a physical change or reaction, or a chemical reaction, matter is neither created nor destroyed. (Lavoisier – 1777) THE …

Atomic mass : The mass of an atom or molecule on a scale where the mass of a carbon-12 (12C) atom is exactly 12.0. The mass of any atom is approximately equal to the total number of its protons and neutrons multiplied by the atomic mass unit, u = 1.6605397 x 10-24 gram. (Electrons are much lighter, about 0.0005486 u.) …