The Ozone theory Flashcards
(54 cards)
Name the four structures of the atmosphere
Troposphere
Stratosphere
Mesosphere
Thermosphere
Define electronegativity
The ability of an atom to attract the bonding pair of electrons in a covalent bond to itself.
Describe 100% ionic bonding
Complete transfer of electrons
Between metal and non metal
Very big differences in electronegativities
Describe 100% covalent bonding
Equal sharing of electrons
Non metals only
Identical electronegativities
Does electronegativity decrease or increase across a period and why?
It increases as number of protons in the nucleus increases. The number of shells stays the same so no change in shielding. The nucleus attracts bonding electrons more strongly.
Does electronegativity decrease or increase along a group and why
Number of shells of electrons increases so this increases shielding. Bonding electrons are further from the nucleus so there’s less attraction between the nucleus and these electrons despite the increased nuclear charge.
Explain covalent bonds with some ionic character
Happens as a result of uneven sharing of bonding electrons.
Occurs when the atoms involved have different electronegativities- the bigger the difference the more polar the covalent bond.
Are hydrocarbons polar or non-polar?
They are non-polar as the difference between Carbon and Hydrogen is very small.
Describe when you would and wouldn’t have a polar molecule
Polar molecule: Permanent overall dipole and individual dipoles do not cancel out.
Non-polar molecule: No overall dipole as its symmetrical the individual dipoles cancel out.
Which bonds are strong and weak?
Ionic, covalent and metallic are strong.
Intermolecular bonds are weak.
Describe instantaneous dipole- induced dipole bonds (IDID)
All molecules have them.
Electrons are constantly moving in molecule.
Uneven distribution of electrons = instantaneous dipole in one molecule.
This causes induced dipoles.
The attraction between two different dipoles is the ID-ID bond.
Describe the trend in boiling and melting point down bigger atoms and molecules groups
MP and BP increase.
More electrons.
More and stronger ID-ID bonds
More energy needed to separate molecules.
What does increased branching in molecule do to the BP and MP?
Decreased BP.
Decreased strength of ID-ID bonds as there is less contact between molecules.
What is permanent dipole- permanent dipole bond?
Attraction between molecules with a permanent dipole.
Stronger than ID-ID bonds.
Exist as well as ID-ID bonds.
Only occur in polar molecules.
What is permanent dipole- induced dipole?
Permanent dipole induces a temporary one in a species that is normally non-polar.
Describe Hydrogen bonds
Strong PD-PD bond.
Is the electrostatic attraction between a H+ and lone pair of electrons.
ONLY occurs when H is bonded to N/O/F.
Define activation enthalpy
The minimum amount of energy required by a pair of colliding particles for a reaction to occur.
Define rate of reaction
The change in concentration of reactants or products with time.
What happens in the concentration of a reactant increases
There are more particles in a given volume and the collision frequency increases.
Describe the effect of pressure on the collision theory
As pressure increases particles are closer together and there are more particles in a given volume. This increases the frequency of collisions.
Describe the effect of surface area on collision theory
Reducing the article size increases SA so more particles are exposed on the surface so there will be a greater frequency of collisions so increases the rate.
Describe the effect of temperature on the collision theory.
Particles have more energy so more collisions ( E> Ea )
Greater proportion of successful collisions. The particles move faster and collide more frequently.
Explain the effect of a catalyst on the collision theory
Provides an alternative route with a low activation energy. A greater proportion of collisions have energy larger than the new Ea. A greater proportion of particles have enough energy to react when they collide. So more successful collisions.
What is a homogenous catalyst and give an example.
Same physical state as reactants and an example is a chlorine radical in the destruction of Ozone. The chlorine radical is regenerated so reacts many times again as a catalyst.
