2.2 Relative mass

define relative isotopic mass

The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12

define relative atomic mass

the weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12

symbol for relative atomic mass

A_r

difference between relative isotopic mass and relative atomic mass

relative isotopic mass is the mass of a single isotope

relative atomic mass is the relative mass of all of the isotopes in a sample.

What is used to find the percentage abundance of the isotopes in a sample of an element?

mass spectrometer

What is the experimental order for mass spectrometry?

1. ionisation

2. acceleration

3. deflection

4. detection

what happens in the ionisation stage?

electrons bombard the atoms to form positive ions

why are the ions separated into isotopes during the acceleration stage?

heavier ions move more slowly and are more difficult to deflect

what does the greater the signal mean for mass spectrometry?

greater the abundance of the isotope

where is the Mr found on a mass spectra?

peak furthest right (greatest m/z)

what does m/z mean?

mass-to-charge ratio

what does m mean?

relative mass of ion

what does z mean?

relative charge on ion