Relative atomic and molecular masses, the Avogardo constant and the mole Flashcards
What is the relative atomic mass (Ar)?
the weighted average mass of an atom of an atom, taking into account its naturally occuring isotopes
it is relative to 1/12 of the relative atomic mass of an atom of carbon 12
average mass of one atom / 1/12 mass of one atom of carbon-12
What is the difference between relative formula mass and relative molecular mass?
relative formula mass is used for ionic compounds because they don’t exist as molecules
both have the symbol Mr
How are atoms counted?
weigh large numbers of them because it is impossible to weigh them individually
How many atoms are in 1g of hydrogen?
6.022 x 10^23
What is the Avogrdo constant?
the number of atoms in 12g of carbon-12
What is a mole?
1 mole is equal to an amount of a substance that contains 6.022 x 10^23 particles
What is the equation for the number of moles?
mass, m (g) / mass of 1 mole M (g)
State why the precise relative atomic mass quoted in the table for the 12C
isotope is exactly 12.00000
by definition
standard / reference value
