Fichas
1.1 Atomic Structure
Fichas del conjunto (14)
- 1Model of the Atom History1. John Dalton- Solid Spheres made up elements
2. Thompson- Plum Pudding model
3. Rutherford, Geiger, Marsden- gold foil experiment=> tiny positive charged nucleus surrounded by cloud of negative electrons
4. Bohr- shells exist in orbits and move between the shells by EM radiation
5.sub-shells (however we use bohr model as simple and fits experimental observations) - 2Relative atomic Mass, Araverage mass of an atom of an element on a scale where an atom of carbon-12 is 12 (an average so not usually whole numbers)
- 3Relative isotopic massmass of an atom of an isotope of an element on a scale where an atom of carbon-12 is 12
- 4Relative molecular mass, Mrthe average mass of a molecule on a scale where an atom of carbon-12 is 12
- 5Relative masses are measured by...Mass Spectrometer measures
-relative atomic mass
-relative isotopic abundance - 6Time Of Flight Mass Spectrometer1. Ionisation
Electrospray ionisation (sample dissolved and pushed through small nozzle at high pressure, high voltage applied so gains H +ion- sample turned into gas made of positive ions)
Electron impact ionisation (sample vaporised and electron gun is used to fire high energy electrons at it, knocking one electron off to become 1+ions)
2. acceleration
positive ions accelerated in electric field so they all have same KE (lighter ones move faster)
3. Ion Drift
ions enter region with no electric field (vacuum/drift region), drift- lighter ions drift faster
4. Detection
lighter ions travel at faster speeds in drift region so reach detector in less time. Detector detects charged particles and mass spectrum is produced. - 7working out Ar from mass spectrum% relative isotopic abundance on y-axis
relative isotopic mass on x-axis
Multiple together to get total mass of isotope
Add up totals and divide by 100 if percentage used. - 8electron configurationsfill the sub shells-
1s 2s 2p 3s 3p 4s 3d 4p
(apart from transition metals Cr and Cu which donate a 4s electron to the 3d sub-shell to become more stable and when they become ions lose 4s electrons before 3d electrons) - 9electronic structure determineschemical properties
- 10First Ionisation energyThe energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions
endothermic as energy is needed to ionise - 11factors effecting ionisation energy1. Nuclear Charge
(increased protons in nucleus, more positively charged the nucleus is and stronger the attraction for the electrons)
2. Distance from Nucleus
(attraction falls with distance from nucleus)
3. Shielding
(num of electrons between outer electrons increases, outer electrons feel less attraction toward nuclear charge=>shielding)
high ionisation energy= high attraction between the electron and the nucleus and so more energy is needed to remove the electron - 12successive ionisation energy/ second ionisation energyeach time you remove an electron...
x (n+1)+ (g) --> x n+ + e- - 13successive ionisation energies show...shell structure;
within each shell successive ionisation energies increase
-increasingly positive ion, less repulsion, held more strongly
big jumps happen when new shells are broken into and electrons are being removed from shell closer to nucleus - 14Trends in first ionisation energies;decrease down a group
(extra electron shell, increased shielding, reduced nuclear attraction)
increase across a period
(n of protons increases, stronger nuclear attraction)
however, group 2 and 3 shows sub shell structure (electrons easier to remove from 3p) and group 5 and 6 show electron repulsion (electrons easier to remove from shared orbitals)
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- A-Level Physical Chemistry Fichas sobre 1.1 Atomic Structure, creado por nicola Goodship el 26/03/2017.
- Creado por
- nicola Goodship · mar 2017
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- 26 mar 2017
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