2.1 Atomic Structure And Isotopes Flashcards
Isotope definition
Atoms of the same element with the same number of proton and electrons and different number of neutrons so different mass number
Relative isotopic mass definition
The mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon 12
Relative atomic mass definition
The weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon 12
What is the difference between relative molecular mass and relative formula mass?
Relative molecular mass is used for simple molecules.
Relative formula mass is used for compounds of giant structures.
What is the difference between properties of isotopes of the same elements?
They may have different melting point, boiling point and density, but the chemical reactions are the same due to electron Number being the same
How to determine relative atomic mass using the mass spectrometer
- sample is placed in the mass spectrometer
- Sample is vaporised and then ionised to form positive ions.
- The ions are accelerated, heavier ions move slowly and are more difficult to deflect then light ions so the ions of each isotope are separated.
- The ions are detected on a mass spectrum as a mass to charge ratio. each ion reaching the detector adds to the signal so the greater the abundance, the larger the signal and the greater the mass to charge ratio
Mass to charge ratio m/z =
Relative mass of ion
——————————
Relative charge on ion
How to work out the accurate relative atomic mass
(Ar of an isotope x abundance) + (Ar of an isotope x abundance) % 100
What is the relative mass of an electron?
1/1836
Formula of ion: zinc
Zn2+
Formula of ion: silver
Ag+
Formula of ion: ammonium
NH4+1
Formula of compound: ammonia gas
NH3
Formula of ion: hydroxide
OH-
Formula of ion: nitrate
NO3-1
Formula of ion: hydrogen carbonate
HCO3-1
Formula of ion: phosphate
PO4 3-
Formula of ion: carbonate
CO3 2-
Formula of ion: sulphate
SO4 2-
How to identify an element given proton number neutron number and mass number
Only use the proton number because it doesn’t change and identify using atomic numbers of elements
Why do different isotopes of the same element have the same chemical properties?
Because of the same number of electrons on the outer shell/same electron configuration
