Relative mass

Question 1

Relative Atomic Mass

Answer 1

• masses of atoms compared to carbon-12
• atoms to small to weigh so 1 atom compared to another
• weighted mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12

Question 2

Relative Isotopic Mass

Answer 2

-mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon-12

Question 3

Relative Molecular Mass

Answer 3

• Mr
• average mass of a molecule, compared to 1/12th of the mass of an atom of carbon-12
• used when referring to simple molecules
• add up relative atomic mass values

Question 4

Relative Formula Mass

Answer 4

• used for compounds that are ionic

- add up relative atomic mass of all ions or atoms in formula unit

Question 5

Relative atomic mass from isotopic abudance

Answer 5

• different isotopes of an element of ur in different quantities or isotopic abundances
• Ar is the average mass of all atoms
• Ar x abundance and add up divide 100

Question 6

Mass Spectra

Answer 6

• produced by mass spectrometers
• used to find out what samples are made up of by the masses of their components
• y-axis = abundance of ions
• height of each peak gives relative isotopic abundance
• x-axis = units a given as a mass/charge ratio

Question 7

Graph Method

Answer 7

• multiply each relative isotopic mass by its relative isotopic abundance and add up results
• divide by sim of isotopic abundances