The Ozone Story

• State what Radicals are

  Radicals are molecules or atoms with at least one unpaired electron. They are very reactive
• What are the two models used to describe light?

  Wave model and particle model
• What are the two key properties of light?

  Wavelength $\lambda$ and frequency $\nu$
• What is the speed of light?

  $c =$$3.00 \times 10^8 \text{ m s}^{-1}$
• What is the relationship between speed, wavelength, and frequency of light?

  $c =$$\lambda \nu$

  
• What constant is represented by $h$ in the equation $E =$$h\nu$?


  Planck constant
• What is the value of the Planck constant $h$?


  $h =$$6.63 \times 10^{-34} \text{ Js}$
• How does electromagnetic radiation interact with matter?

  It transfers energy to the chemicals involved
• What are the different aspects of a molecule's energy?

  • Translation: whole molecule movement
  • Rotation: whole molecule rotation
  • Vibration: bond vibrations
  • Electrons: excitation, dissociation, ionisation

  
• Which part of the spectrum corresponds to vibrational energy levels?

  Infrared part of the spectrum
• What happens to bonds in chemicals when exposed to infrared radiation?

  Bonds vibrate more energetically
• Which requires less energy: rotation or vibration?

  Rotation requires less energy than vibration
• What requires the least energy among translational, rotational, and vibrational changes?

  Translational changes require the least energy
• Which electronic changes require the most energy?

  Exciting electrons to higher levels
• What happens when a chlorine molecule absorbs radiation?

  Electrons can be excited to a higher level
• What color does chlorine absorb that affects its appearance?

  Visible light, leaving green color
• What can happen to chlorine molecules when they absorb high-energy radiation?

  They can undergo photodissociation
• What are radicals?

  Molecules with at least one unpaired electron
• What occurs when molecules are ionised by high energy?

  An electron leaves the molecule
• What is the equation for the relationship between speed, wavelength, and frequency?

  $c =$$\lambda \nu$

  
• What is the equation for energy in terms of frequency?

  $E =$$h\nu$
• What are the parts of the electromagnetic spectrum mentioned?

  Infrared, red, green, blue, ultraviolet
• How do atmospheric gases affect solar radiation?

  They absorb ultraviolet radiation
• Which gas absorbs most high-energy radiation below 241 nm?

  Oxygen
• What is the role of ozone in the atmosphere?

  Absorbs strongly in the 296–214 nm region
• What is the role of sulphur dioxide in the atmosphere?

  Minor trace gas with small role
• What types of radiation reach the Earth's surface?

  Infrared, visible, and near ultraviolet
• Why is the absorption of ultraviolet radiation important?

  It can cause damage to living tissue
• Does water cut out ultraviolet radiation in sunlight?

  No, it does not
• Can you tan through glass?

  No, glass absorbs ultraviolet radiation
• What is the main absorption characteristic of olive oil?

  Absorbs in visible and near UV areas
• What is a good sunscreen according to the study material?

  1. aminobenzoic acid
• What does 4-aminobenzoic acid do?

  Absorbs harmful ultraviolet radiation
• What is hydrolysis in the context of halogenoalkanes?

  Reaction with water that breaks down compounds
• Why is heat required for the hydrolysis of halogenoalkanes?

  It facilitates the reaction under reflux conditions
• What are the products of the hydrolysis of halogenoalkanes?

  An alcohol and a halide

  
• What is the most common source of aqueous hydroxide ions for hydrolysis?

  Aqueous sodium hydroxide
• What is the nucleophilic substitution mechanism in hydrolysis?

  Hydroxide ion attacks electron deficient carbon
• Why is the bond between halide and carbon in halogenoalkanes polar?

  Halide atoms are more electronegative than carbon
• What happens to the shared electrons during the nucleophilic substitution?

  They are repelled onto the halogen atom