What is the difference between a compound and a molecule?

[kjamha]

I have read several definitions that basically say a molecule is formed when two or more atoms join together chemically. And a compound is a molecule that contains at least two different types of atoms. All compounds are molecules but not all molecules are compounds.

Examples of molecules include H2O, O2, O3 and examples of compounds include NaCl, H2O.

Giancoli's text states that "compounds are substances made up of elements, and can be broken down into them; examples include carbon dioxide and water. The smallest piece of an element is an atom; the smallest piece of a compound is a molecule. Molecules are made of atoms."

I would interpret Giancoli's definition to say that an H2O molecule by itself is not a compound - but a collection of H2O molecules IS a compound. The same way that a gold atom by itself is not an element, but a collection of gold atoms is an element.

Is my interpretation way off?

 

[sophiecentaur]

That sounds ok to me but, really, why lose sleep over that? I cannot think of a situation where the could be confusion generated and that's the only time that terminology or classification may be important.

 

[TumblingDice]

Giancoli's text states that "compounds are substances made up of elements, and can be broken down into them; examples include carbon dioxide and water. The smallest piece of an element is an atom; the smallest piece of a compound is a molecule. Molecules are made of atoms."

I would interpret Giancoli's definition to say that an H2O molecule by itself is not a compound - but a collection of H2O molecules IS a compound. The same way that a gold atom by itself is not an element, but a collection of gold atoms is an element.

Is my interpretation way off?

That's not what the text intended to imply. A gold atom by itself is indeed an element and one molecule of water is a compound. These are the smallest either one can be reduced and still remain an element and a compound, respectively.