جميع المواضيع المتعلقة بـ ‘Atomic mass’

 

simplified chemistry – atoms notes (cards)

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 LAW OF DEFINITE COMPOSITION

A compound always contains…

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Atomic mass

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.) No atom differs from this simple formula by…

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