Chm Diagnostic

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Chm 11-2

protons- positively charged particles

neutrons- no charge

electrons - negatively charge particles

mass number (A) = atomic number (Z) + number of neutrons

isotopes- same atomic number but different atomic mass

diatomic molecule- contains only two atoms.

polyatomic molecules- contains two or more atoms.

cation (+)- positively charge ions; gives away electrons

anion (-) - negatively charged ions; receive electrons from a atom that is a cation

(Joseph Proust) Law of definite proportion- diff samples of the same compound always contain its constituent elements in the same proportion by mass.

Molecular Compounds- usually composed of nonmetallic elements