Atomic structure Flashcards
define relative mass
the mass of particles compaared to a proton
define mass number
proton number + neutron number
define relative atomic mass
the average mass of an atom relative to 1/12 of a carbon 12 atom
do isotopes react the same as atoms, why
yes, they have the same electron configuration
how do you calculate relative atomic mass
total number of all atoms
AKA
total abundance
what is the mass spectrometer used for
to determine the relative atomic mass
what does the time of flight mass spectrometer detect
the mass and relative abundance of iosopts in elements
what condition must the TOF mass spectrometer be used in
a vacum so that ions dont colide with air molecules
what are the 4 stages of the TOF mass spectrometer
ionisation
acceleration
flight tube drift
detection
what are the two type of ionisation used for the TOF mass spectrometer and what are they used for
electron impact method - elements
electrospray method - large molecules
what happens during electron impact ionisation (3)
- sample is vaporised
- an electron gun (current carrying wire) emits high energy electrons that knock electrons of the elements
- forms a 1+ ion
what happens during electrospray ionisation (4)
- sample is disolved
- sample pass through a hypodermic needle attached to postive high voltage power
- producs 1+ charged droplets
- Solvent evaporates from droplets in the vacum to form a fine mist
what happens during acceleration in a TOF mass spectrometer (2)
- ions are accelerated by an electric field so they all have the same KE
- lighter and more highly charged ions achieve a higher speed
what happends during flight tube drift in a TOF mass spectrometer (3)
- ions travel in a beam
- attracted to the negatively charge detector plate
- the ions travel at different speeds so take different times to reach the detector
which types of ions reach the detector first in a TOF mass spectrometer
lighter ions
what happens during detection in a TOF mass spectrometer (2)
- positive ions hit a negaitvely charged plate
- every collision produces an electric current proportional to the number of ions
what type of data does the TOF mass spectrometer produce
a mass spectrum
what are the two axis on a mass spectrum
x axis = m/z (mass to charge ratio)
typically just the mass of a particle as charge = 1
y axis = percentage / relative abundance
what do the number of peaks represent on a mass spectrum
the number of isotopes present
how do you predict the amount of peaks on a mass spectrum
work out the number of possible isotopes combinations
what is an orbital
a region where it is likely to find an electron
one orbital can hold 2 electrons
how many electrons can fit in the s sub level
2
how many electrons can fit in the p sub level
6
what does the s sub level look like
a sphere
what does the p sub level look like
a funny flower with 6 petals
3 orbitals
how many electrons can the d sub level hold
10
how many electrons can the f sub level hold
14
how many electrons can the follow energy levels hold
1
2
3
4
1 - 2
2 - 8
3 - 18
4 - 32
do electrons pair to in an orbit to begin with
no, they fill all the orbitals with one, then pair
what is the order of energy levels being filled.
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d
how is the electron configuration of Chromium and copper different from normal
an electron is promoted from 4s and is transfered to 3d (4s has one electron and 3d has 1 electron in each orbital)
what happens when transition metals lose electrons
they lose them from 4s first, then 3d
define first ionisation energy
the energy require to remove one mole of electrons from one mole of gaseous atoms to produce one mole of gaseous 1+ ions
what is the equation for the first ionisation energy of sodium
Na -> Na+1 + e-
how would you write the second ionisation energy of sodium
Na+ -> Na+2 + e-
how can you tell a new energy level has been reached based on successive ionisation energies, how can you tell the group number based on this
there will be a big jump in energy
the group number will be the number of ionisation energies before the big jump
why does ionisation energy decrease going down a group
- more shells
- more electron shielding
- greater distance between the outer shell electrons and nucleus
- less attraction between nucleus and outer electrons
what happens to atomic radius going down a group? going across a period?
down a group - always increases
across a period - generally decreases
why does ionisation energy generally increase as you go along a period
- number of protons is greater, so nucleur charge is greater
why do first ionisation energies dip as you enter a new sub level
- the electron is alone, so easier to lose
- electron is further from the nucleus
why do first ionisation energies dip when an element has more paired electrons in its sub levels
the electron is repelled by its paired electron, so loses it easier
