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AQA Chemistry > Physical 1 Section 1 - Unit 1: Atomic Structure > Flashcards

Physical 1 Section 1 - Unit 1: Atomic Structure Flashcards

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1
Q

Explain why sulphur has a lower ionisation energy than phosphorus (2 marks)

A
  • Sulphur’s outer 3p orbital is full so there is repulsion between the electrons
  • Meaning that less energy is needed to remove one of these paired electrons
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2
Q

State any differences and similarities (if any) in the atomic structure and chemistry of the isotopes of an element. (4 marks)

A
  • Different number of neutrons
  • Same atomic number
  • Same chemical properties
  • Because same electron configuration
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3
Q

Explain why magnesium has a higher melting point than sodium (2 marks)

A
  • Magnesium has more protons

- So it attracts the delocalised electrons more strongly

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4
Q

Explain why metals are malleable (2 marks)

A
  • The attractive forces are the same throughout the metal lattice
  • So the ions in the lattice can slide over each other
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5
Q

Explain why S8 has a higher melting point than P4 (2 marks)

A
  • Sulphur has a greater Mr

- So there are stronger Van der Waals forces

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6
Q

Explain why the boiling points of Hydrogen Halides increases down a group (2 marks)

A
  • The size of the Van der Waals forces

- Increases with the increasing size of the electron cloud

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7
Q

State whether aluminium or magnesium has a lower ionisation energy and explain why (3 marks)

A
  • Aluminium
  • Because the outer electron is in a higher 3p subshell
  • Which is higher in energy and further away from the nucleus meaning that less energy is needed to remove the electron
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8
Q

Explain why the melting point decreases down group 2 (2 marks)

A
  • Atomic radius increases down a group

- So there is weaker metallic bonding (due to the weaker force on delocalised electrons)

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9
Q

Explain what is meant by the term relative isotopic abundance (2 marks)

A
  • Ratio abundance of each isotope

- Present in a sample of the element

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10
Q

Explain why silicon has a high melting point (3 marks)

A
  • Silicon is macromolecular
  • Meaning that the covalent bonds need to be broken
  • And these bonds are very strong and require a lot of energy to be broken
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11
Q

Describe what change occurs to the motion of the ions in sodium chloride when it is heated from room temperature to a temperature below its melting point (1 mark)

A
  • The ions vibrate faster
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12
Q

Explain why O-H is polar (2 marks)

A
  • Oxygen is more electronegative than hydrogen

- And this causes a higher electron density around oxygen atom

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13
Q

Explain why it is necessary to ionise molecules when measuring their mass in a TOF mass spectrometer (2 marks)

A
  • Only ions will be accelerated by an electric field

- Only ions will create a current when hitting the detector

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14
Q

Describe how ions are formed by electrospray in a TOF mass spectrometer (2 marks)

A
  • Sample is dissolved in a polar solvent and passed through a positive terminal with a high voltage
  • Molecules gain a proton
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15
Q

Explain what accelerates the ions before they are deflected in mass spectrometry (1 mark)

A
  • Electric field
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16
Q

Explain what deflects the moving ions round a curved path in mass spectrometry (1 mark)

A
  • Magnet
17
Q

State what is adjusted in a mass spectrometer in order to direct ions with different m/z values onto the detector (2 marks)

A
  • Electric/ magnetic field

- So that the deflection of ions onto the detector generates an electric current

18
Q

Explain how ions are detected and relative abundance is measured in a TOF mass spectrometer (2 marks)

A
  • Ion hits the negative plate and gains an electron

- And relative abundance is proportional to the size of the current produced

19
Q

Explain the increase in melting point from sodium oxide to magnesium oxide (2 marks)

A
  • Greater charge density on magnesium ion

- So there’s stronger ionic bonding

20
Q

Explain why the melting point of the oxide of silicon is much higher than that of the highest oxide of phosphorus (3 marks)

A
  • SiO2 is macromolecular
  • P4O10 is simple molecular
  • Covalent bonds of SiO2 are much stronger than the intermolecular forces in P4O10
21
Q

Explain why silicon dioxide has a higher melting point than sulphur trioxide (4 marks)

A
  • Covalent bonds in SiO2
  • Van der Waals forces in SO3
  • Covalent bonds are stronger than van der Waals forces
  • And so they require more energy to be overcome/broken
22
Q

Explain the process of a mass spectrometer (6 marks)

A
  • The sample is dissolved in a volatile, polar solvent
  • And passed through a positive terminal with a high voltage
  • This causes the sample to gain a proton and become positively charged
  • Positive ions are accelerated by an electric field
  • To a constant kinetic energy
  • The positive ions with smaller m/z values will have the same kinetic energy as those with larger m/z and will move faster
  • The ions hit the negative plate and gain an electron
  • And relative abundance is proportional to the size of the current produced
23
Q

Define the term relative atomic mass (2 marks)

A
  • Average mass of one atom compared to one twelfth of the mass of one atom of carbon-12
24
Q

In a mass spectrometer, the relative abundance of each isotope is proportional to the current generated by that isotope at the detector. Explain how this current is generated (1 mark)

A
  • Electrons transferred

- From the detector to the positive ion

25
Q

Name the three processes that occur in a mass spectrometer before the vaporised isotopes can be detected and state how each process is achieved (6 marks)

A
  • Ionisation
  • High energy electrons fired at sample
  • Acceleration
  • With electric field
  • Deflection
  • With magnetic field
26
Q

Explain why two different compounds with the same molecular formula can still be separated via electrospray ionisation (1 mark)

A

Precise masses are different

AQA Chemistry (32 decks)

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