مصادر الكيمياء موقع لتعليم الكيمياء بصورة مبسطة
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 …
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