Chem (basic concept)

Molecule------是一些element 由covalent bond 組成的最基本單位(eg.H-H / H2)，一旦拆開了(很難)，功能就沒有了。

Compound-------是由多於兩種or以上的element 組成最基本單位的統稱
(eg. NaCl is an ionic compound ), (eg. CO2 is a covalent compound, )
(eg. but H2 is not a compound because it (the molecule) only consist(have) of one kind of element.

2006-12-08 18:08:26 補充：
The molecules of an "element" consist of atoms of the "same" element. The molecules of a "compound" consist of atoms of the "different" element.

a molecule can be a compound