The Ozone Story

Question 1

Define electro negativity

Answer 1

The ability of an atom to attract the bonding electrons in a covalent bond

Question 2

How are pola covalent bonds formed?

Answer 2

Atoms with different electro negativity, electrons attracted to the more electronegative atom more
So they are spread unevenly

Question 3

What does the polarity of a molecule depend on?

Answer 3

It’s shape- if symmetrical it is non polar

Question 4

Name the 3 intermolecular bonds in order of strength getting stronger

Answer 4

Instantaneous dipole- indices dipole bonds

Permanent dipole-permanent dipole bonds

Hydrogen bonding

Question 5

Which atoms have stronger ID-ID bonds?

Answer 5

The heavier- bigger atoms as they have more electrons

Question 6

What two factors influence the boiling point of organic molecules? And why?

Answer 6

Length of the chain
- longer means stronger idid bonds as more molecular surface contact

Branching
- less branching means more surface contacts so more Idid bonds form

Question 7

What atoms does hydrogen bonding form between?

Answer 7

Hydrogen and either fluorine, nitrogen or oxygen

Question 8

Why is ice less dense than water?

Answer 8

Water molecules are arranged for maximum number of hydrogen bonds so form a lattice

As these bonds get broken, lattice breaks down and ice melts

Question 9

What is activation energy?

Answer 9

Energy pairs of molecules need to react when they collide

Question 10

What do catalysts do increase rate of reaction?

Answer 10

Provide an alternative reaction pathway with a lower activation energy

Question 11

What is a homogeneous catalyst and how does it work?

Answer 11

Catalyst at same state as reactants
They work by forming intermediate compounds with the reactants then the product is formed from this
Overall needs a lower activation energy

Question 12

What is the trend of boiling points of haloalkanes?

Answer 12

Boiling point increases down the group

Atomic radius of halogens increase down the group leading to stronger IDID bonds

More energy needed to overcome

Question 13

What is formed when a haloalkane undergoes nucelophillic substitution with hydroxide ions, water and ammonia?

Answer 13

Alcohol + halogen ion

Alcohol +halogen ion + hydrogen ion

Amine + ammonia/ammonium

Question 14

What is the trend in reactivities of haloalkanes?

Answer 14

Reactivity increases down the group

Bond enthalpy decreases down group- needs to b broken for reaction due to smaller atomic radius

Question 15

Define heterolytuc fission and where does it occur?

Answer 15

Uneven split of electrons - due to different electronegativity

Question 16

Define homolytic fission and where does it occur?

Answer 16

Even split of electrons within a bond forming radicals

Happens in molecules of a single atom and often in gases in stratosphere due to UV by photodidsociation

Question 17

What acts as catalysts in the catalytic cycle of the breakdown of ozone and how is it formed?

Answer 17

Halogen radicals and other radicals

Formed by photodissociation

Question 18

What are the effects of ozone in the stratosphere?

Answer 18

Absorb high energy uv light

Without cancer

Question 19

What are the effects of ozone in the troposphere?

Answer 19

Photochemical smog and respiratory problems

Question 20

What can uv and visible light do to electrons?

Answer 20

Promote to higher energy levels

Question 21

explain the meaning of a propogation reaction?

Answer 21

when radicals react to produce new radicals to continue the reaction