relative mass Flashcards
1
Q
what is the relative atomic mass (Ar)?
A
- the average mass of an atom of an element on a scale where an atom of carbon 12 is exactly 12
2
Q
where is the relative atomic mass of each element shown?
A
in the periodic table
3
Q
what is the formula for relative atomic mass?
A
(mass number x abundance) + (mass number x abundance) /100
4
Q
why is relative atomic mass not ususally a whole number?
A
- because its an average
5
Q
what is relative isotopic mass of an atom?
A
- the mass of an atom of an isotope of an element on a scale when an atom of carbon 12 is exactly 12
6
Q
is relative isotopic mass a whole number?
A
- yes its usually a whole number
7
Q
what do most elements have?
A
- more than one isotope
8
Q
what is the relative molecular mass (Mr)?
A
- the average mass of a molecule on a scale where one atom of carbon 12 is exactly 12
9
Q
how do you find the Mr of a molecule?
A
- just add the relative atomic mass values of all the atoms in the molecule
10
Q
what is relative formula mass?
A
- the average mass of a formula unit on a scale where an atom of carbon 12 is exactly 12
11
Q
what is relative formula mass used for?
A
- for compounds that are ionic (or giant covalent)
12
Q
how do you find the relative formula mass?
A
- add the relative atomic masses of all the ions in the formula unit
