What's the difference between a formula unit and a molecule?

1 Answer
Dec 17, 2014

Answer:

A molecule is composed of two or more elements that are covalently bonded.

A formula unit indicates the lowest whole number ratio of ions in an ionic compound.

Explanation:

A molecule is composed of two or more elements that are covalently bonded. It is the smallest particle of a covalent substance that has all of the properties of that substance, and it is the smallest particle of that substance that can participate in a chemical reaction. The following diagram shows the formation of four different molecules through covalent bonding.

http://chemwiki.ucdavis.edu/Organic_Chemistry/Fundamentals/Introduction_to_Organic_Chemistry

A formula unit indicates the lowest whole number ratio of ions in an ionic compound. Because the positively and negatively charged ions in an ionic compound are arranged in a crystal lattice, there is no discrete particle comparable to a molecule.

http://schools.bcsd.com/fremont/5th_sci_matter_salt.htm