جميع المواضيع المتعلقة بـ ‘Atoms’

 

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 nucleus

Atomic nucleus The central region of an atom. Atoms are composed of nega­tively charged electrons, positively charged protons, and electrically neutral neutrons. The protons and neutrons (collectively known as nucleons) are located in a small central region known as the nucleus. The electrons move in orbits which are large in comparison with the dimensions of the nucleus itself. Protons and neutrons possess ap­proximately equal masses, each roughly 1840…

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