3.2 Masses of Atoms, Molecules and Ions Flashcards
1
Q
What is Carbon-12?
A
The masses of all atoms are relative to 1/12 of Carbon-12.
2
Q
What is Ar?
A
The relative atomic mass of an atom is the average mass of its isotopes, relative to 1/12 of a carbon-12 atom.
3
Q
How is the mass of a molecular substance calculated?
A
Sum of all Ar values in a single molecule = Mr
4
Q
How is the mass of an ionic substance calculated?
A
Sum of all Ar values in formula = Mr
5
Q
Laws of chemistry:
A
- Elements always react in the same ratio, to form a given compound.
- Total mass of reactants = total mass of products.
6
Q
Percentage composition calculation:
A
- Write down formula.
- Find Mr.
- Write mass of element as a fraction of Mr.
- Multiply by 100 to find percentage.
7
Q
What is Mr?
A
