Ozone Flashcards
What is electronegativity?
The ability of an atom in a molecule to attract electrons in a chemical bond to itself.
What is the trend of electronegativity across a period?
Electronegativity increases across a period.
What is the trend of electronegativity down a group?
Electronegativity decreases down a group (excluding noble gases).
Which element is the most electronegative?
Fluorine, with an electronegativity of 4.0.
What creates a polar covalent bond?
A difference in electronegativity between two bonding atoms.
What is the polarity of a C-F bond?
C δ+ — F δ-, where carbon is partially positive and fluorine is partially negative.
What is a dipole?
A molecule with a positive end and a negative end due to charge difference.
What are instantaneous dipoles?
Temporary dipoles formed when electrons are unevenly distributed in a molecule.
What are instantaneous dipole-induced dipole bonds?
Weak intermolecular bonds formed when an instantaneous dipole polarises a nearby molecule.
What is a permanent dipole?
A dipole formed when two atoms in a bond have different electronegativities and charges don’t cancel.
What is the trend in boiling points for halogens?
Boiling points increase down the group due to stronger instantaneous dipole-induced dipole bonds.
What causes stronger intermolecular forces in alkanes?
Longer carbon chains and larger molecular surface areas.
What is the experimental test for permanent dipoles in a liquid?
Use a charged rod near a liquid jet; deflection indicates permanent dipoles.
What are hydrogen bonds?
The strongest type of intermolecular bond, formed when H is covalently bonded to F, N, or O.
Why does ice float on water?
Ice has an open lattice structure, making it less dense than liquid water.
What properties do liquids with hydrogen bonds have?
High viscosity, high melting/boiling points, and solubility in water.
What is activation enthalpy?
The minimum energy required for particles to react upon collision.
What do catalysts do in a reaction?
Provide an alternate pathway with lower activation enthalpy.
What happens to the rate of reaction as concentration increases?
It increases due to more frequent collisions.
What is the effect of increasing temperature on reaction rate?
Increases rate by raising particle energy and frequency of collisions.
What does a Maxwell-Boltzmann distribution show?
The spread of kinetic energy among particles in a gas.
How do catalysts affect the Maxwell-Boltzmann distribution?
Lower the activation energy, allowing more particles to react.
What is the formula for the speed of light?
c = λ × ν, where λ is wavelength and ν is frequency.
How is photon energy calculated?
E = h × ν, where h is Planck’s constant and ν is frequency.
What are haloalkanes?
Alkanes with at least one hydrogen atom replaced by a halogen atom.
What makes a haloalkane reactive?
The polar carbon-halogen bond, where the carbon is electron-deficient.
What is nucleophilic substitution?
A reaction where a nucleophile replaces an atom or group in a molecule.
What happens when water acts as a nucleophile?
It hydrolyses haloalkanes, forming alcohols and H⁺ ions.
What happens to C-X bond reactivity down group 7?
Reactivity increases due to decreasing bond enthalpy.
What is a radical?
A molecule with an unpaired electron.
What is homolytic fission?
A bond breaks evenly, with each atom receiving one electron.
What is heterolytic fission?
A bond breaks unevenly, with one atom receiving both bonding electrons.
What are the three stages of a radical chain reaction?
Initiation, propagation, and termination.
What is the role of chlorine radicals in ozone depletion?
They catalyse the breakdown of ozone into oxygen.
What is the overall reaction for ozone breakdown?
O₃ + O● → 2O₂.
What are the effects of ozone in the stratosphere?
Absorbs UV radiation, reducing its harmful effects on Earth’s surface.
What are the effects of ozone in the troposphere?
It is a pollutant that causes photochemical smog and respiratory problems.
What is the role of UV radiation in ozone formation?
UV dissociates O₂ molecules, forming radicals that create ozone.
What is photodissociation?
The breaking of a chemical bond due to absorption of light energy.
What is the electromagnetic spectrum?
Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
How is ozone both formed and destroyed?
O₂ + UV → O●, O● + O₂ → O₃; UV can also split O₃ into O₂ + O●.
What does the speed of light in a vacuum equal?
3.00 × 10⁸ m/s.
Why is ozone depletion concerning?
It allows more harmful UV radiation to reach Earth’s surface, increasing health risks.
What is the effect of radicals like NO● on ozone?
They catalyse the destruction of ozone, similar to chlorine radicals.
Why is C-F less likely to break than C-I?
C-F has the highest bond enthalpy, while C-I has the lowest.
What happens when haloalkanes reach the stratosphere?
They release radicals that deplete ozone.
