(1) atomic structure

Question 1

Dalton’s model

Answer 1

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

Question 2

Thompson’s model

Answer 2

• 1897
• Plum pudding
• Electrons embedded in positive mass

Question 3

Rutherford’s model

Answer 3

• 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

Question 4

Bohr’s model

Answer 4

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

Question 5

Modern model

Answer 5

• Subshells

Question 6

Relative Atomic Mass

Answer 6

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

Question 7

Relative isotopic Mass

Answer 7

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

Question 8

Ar formula

Answer 8

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

Question 9

Relative Molecular Mass

Answer 9

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

Question 10

Relative Formula Mass

Answer 10

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

Question 11

Electrospray ionisation

Answer 11

• 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)

Question 12

Electron impact ionization

Answer 12

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

Question 13

Acceleration stage

Answer 13

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

Question 14

Ion drift stage

Answer 14

• No electric field

- Lighter ions drift faster

Question 15

Detection stage

Answer 15

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

Question 16

Ionisation stage

Answer 16

• So sample can be accelerated by electric field

- So current can be produced at detector

Question 17

Molecular ion peak

Answer 17

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

Question 18

4s sub-shell

Answer 18

• Lower energy level than 3d

- Fills before 3d

Question 19

Hun’s rule

Answer 19

• Electrons fill shells singularly before they start pairing up

Question 20

Transition metal exceptions

Answer 20

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

Question 21

Transition metal ionization

Answer 21

• Loose their electrons from their 4s subshell before 3d

Question 22

First ionisation energy

Answer 22

• 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-

Question 23

Nuclear charge

Answer 23

• More protons in nucleus = stronger attraction to valence electrons

Question 24

Distance from nucleus

Answer 24

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

Question 25

Shielding

Answer 25

-More shells between valence shell and nucleus = less attraction

Question 26

Second ionisation energy

Answer 26

- 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

Question 27

Successive ionisation

Answer 27

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

Question 28

Ionisation down group 2

Answer 28

- Decreasing ionisation energy because distance from atom and shielding increases

Question 29

Ionisation across periods

Answer 29

- 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

Question 30

Successive ionisation trend (single atom)

Answer 30

- Energy increases within shells because nuclear charge increases - Jumps happen when new shell is broken into, because closer to nucleus

Question 31

Proof of shell structure

Answer 31

- Ionisation energies