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AS level Chemistry (aqa) > (1) atomic structure > Flashcards

(1) atomic structure Flashcards

1
Q

Dalton’s model

A
  • 19th cent.
  • Atoms = solid spheres
  • Different spheres made up different elements
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2
Q

Thompson’s model

A
  • 1897
  • Plum pudding
  • Electrons embedded in positive mass
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3
Q

Rutherford’s model

A
  • 1909
  • Gold foil experiment
  • Tiny + nucleus (most alpha particles went straight through)
  • Cloud of - electrons (some alpha particles deflected backwards)
  • Most of atom is empty space
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4
Q

Bohr’s model

A
  • Electrons in fixed shells
  • Shells have fixed energy
  • EMR is emitted/absorbed when electron jumps between shells (has a fixed frequency)
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5
Q

Modern model

A
  • Subshells
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6
Q

Relative Atomic Mass

A

-The average mass of an atom of an element compared to 1/12th the mass of a carbon 12 atom

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7
Q

Relative isotopic Mass

A

-The mass of an atom of an isotope of an element compared to 1/12th the mass of a carbon 12 atom

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8
Q

Ar formula

A

Sum of the product of isotopic masses and relative abundance / 100

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9
Q

Relative Molecular Mass

A

-The average mass of a molecule compared to 1/12th the mass of a carbon 12 atom

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10
Q

Relative Formula Mass

A

-Average mass of a formula unit compared to 1/12th the mass of a carbon 12 atom

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11
Q

Electrospray ionisation

A
  • Sample dissolved in polar solvent (water/ethanol)
  • Pushed through nozzle at high pressure
  • High voltage applied
  • Particles gain H+ ion
    -(m/z value 1 unit greater on spectrum due to proton)
    X(g) + H+(g) -> XH+(g)
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12
Q

Electron impact ionization

A
  • Sampled is vaporized
  • High energy electrons fired with electron gun
  • Knocks 1* electron off
  • *Sometimes more
    X(g)-> X+(g) + e-
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13
Q

Acceleration stage

A
  • Ions accelerated by electric field
  • All ions have same kinetic energy
  • Lighter ions accelerate faster than heavier ones
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14
Q

Ion drift stage

A
  • No electric field

- Lighter ions drift faster

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15
Q

Detection stage

A
  • Lighter ions reach detector first
  • Detector records the current created when ion arrives and time taken to travel through spectrometer
  • Mass/charge value calculated
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16
Q

Ionisation stage

A
  • So sample can be accelerated by electric field

- So current can be produced at detector

17
Q

Molecular ion peak

A
  • Tallest peak to the right
  • Mr of molecule in sample
  • Multiple if sample contains compounds made of different isotopes
18
Q

4s sub-shell

A
  • Lower energy level than 3d

- Fills before 3d

19
Q

Hun’s rule

A
  • Electrons fill shells singularly before they start pairing up
20
Q

Transition metal exceptions

A
  • Chromium and Copper donate a 4s electron to the 3d subshell to be more stable
21
Q

Transition metal ionization

A
  • Loose their electrons from their 4s subshell before 3d
22
Q

First ionisation energy

A
  • Energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions
  • Endothermic
  • X(g) -> X+(g) + e-
23
Q

Nuclear charge

A
  • More protons in nucleus = stronger attraction to valence electrons
24
Q

Distance from nucleus

A
  • Valence shell electrons further from nucleus = less attraction between the two
25
Q

Shielding

A

-More shells between valence shell and nucleus = less attraction

26
Q

Second ionisation energy

A
  • Higher than 1st ionisation

- Energy required to remove 1 electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of 2+ ions

27
Q

Successive ionisation

A

X(n-1)(g) -> X(n+)(g) + e-

28
Q

Ionisation down group 2

A
  • Decreasing ionisation energy because distance from atom and shielding increases
29
Q

Ionisation across periods

A
  • General increase because increasing number of protons so nuclear charge increases
  • Drops between groups 2 and 3 show changes in subshells because it gets closer to nucleus
  • Drops between 5 and 6 due to electron pair repulsion
30
Q

Successive ionisation trend (single atom)

A
  • Energy increases within shells because nuclear charge increases
  • Jumps happen when new shell is broken into, because closer to nucleus
31
Q

Proof of shell structure

A
  • Ionisation energies

AS level Chemistry (aqa) (2 decks)

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