atomic structure

Question 1

define mass number

Answer 1

sum of protons and neutrons in a atome

Question 2

define atomic number

Answer 2

number of protons in an atom

Question 3

how to find the neutron number?

Answer 3

-mass number- atomic number

Question 4

define relative atomic mass

Answer 4

-mr= mass number of an atom of an element/1/12 x mean mass of C-12isotope

Question 5

what is mass spec used for?

Answer 5

-used to identify different isotopes and find the overall relative atomic mass of an element

Question 6

how does time of flight mass spec show isotope number?

Answer 6

-records the time taken for each isotope to reach the detector

Question 7

what occurs in the ionisation step?

Answer 7

-ELECTROSPRAY IONISATION= the sample is dissolved and pushed through a small nozzle at high pressure, a voltage is applied, causing each particle to gain a H+ ion, sample is turned into a GAS made up of positive ions.
ELECTRON IMPACT= the sample is vaporised and a ‘electron gun’ is used to fire high energy electrons at it, knocking one electron off each particle so they gain +1 ions

Question 8

what happens in the acceleration step?

Answer 8

-positively charged ions are accelrated by electric feild so THEY ALL HAVE THE SAME KE.

Question 9

what happens in the ion drift step?

Answer 9

-the ions enter a region with no electric feild so they just drift. LIGHTER ions will drift FASTER, than heavier ones

Question 10

what happens in the detection stage?

Answer 10

-as lighter ions travel faster than heavier ions, they reach the detector in LESS time than heavier ions. the detector detects charged particles and a mass spec is producved?