[MeanMino]

I was wondering what unit of measurement is used for the atomic masses on the periodic table of elements.

[sjb]

I was wondering what unit of measurement is used for the atomic masses on the periodic table of elements.

These are all effectively ratios, such that the number you would see for a ¹²C isotope is 12.000 (by definition). An Avogadro's number of atoms would have a mass of that value in grams.

[MeanMino]

Sorry, I'm in 7th grade. Didn't really understand a word of that.

[Arkcon]

The units for atomic mass are AMU, that stands for ... atomic mass units.  Like sjb: already told you, they were determined as ratios, so the units in the calculation have cancelled out.  We relate them to actual mass that me can measure using Avogadro's number, but that is also a theoretical, it's not like someone counts each one out until 6.200 X 10²³.  See if any of those concepts ring a bell for you, and if you can find them in your textbook, see if you can pull it all together into a response your instructor will like.

[fledarmus]

It has also been defined as "unified atomic mass unit" with symbol "u", and as "Dalton" with symbol "Da". Personally I have never seen "u" used outside of books of basic definitions, and Daltons is used mainly for the very large (comparatively) masses of proteins, where kiloDaltons (kDa) is more helpful.