The Ozone Story Flashcards

1
Q

What is electronegativity?

A

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

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2
Q

What is electronegativity measure using?

A

Pauling Scale

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3
Q

What is the most electronegative element?

A

Fluorine with a value of 4.0 on the Pauling scale

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4
Q

What happens to electronegativity in periods and groups?

A
  1. Increases across periods
  2. Decreases down groups (ignoring the noble gases)
  3. Increases as you move towards fluorine
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5
Q

Where do the bonding electrons sit in covalent bonding and when will it be non-polar?

A

They sit in orbitals between the two nuclei. If they have similar or identical electronegativities, the electrons will sit roughly midway between he nuclei and the bond will be non polar

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6
Q

Are the covalent bonds in homonuclear (diatomic gasses) polar or non-polar and why?

A

Non-polar because the atoms have equal electronegativities and so electrons are equally attracted to both nuclei

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7
Q

What occurs if the bond between two atoms have different electronegativities?

A

The bonding electrons will be pulled towards the more electronegative atom, causing the electrons to be spread unevenly so there will be a charge across the bond (each atom will have a partial charge, + or -) and the bond is said o be polar

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8
Q

How can you predict if the bond is polar or non-polar?

A

If the difference in electronegativity is more than 0.4

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9
Q

What does a molecule rely on to be polar?

A

The shape and the polarity of the bonds

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10
Q

What is one characteristic of a polar molecule? (dipole)

A

It had an overall dipole (sometimes referred to as overall polarity) caused by the presence of a permanent charge across the molecule

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11
Q

What occurs in a simple molecule when it comes to electronegativity?

A

The polar bond gives the whole molecule a permanent dipole and is polar

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12
Q

What occurs in a more complex molecule when all the polar bonds are arranged so they point in opposite directions?

A

They will cancel each other out and the molecule is non-polar overall

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13
Q

What occurs in a more complex molecule when all bonds point roughly in the same direction?

A

The molecule will be polar

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14
Q

What are intermolecular bonds?

A

Forces between molecules that are much weaker than covalent, ionic and metallic bonds.

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15
Q

What are the 3 types of intermolecular bonds?

A
  1. Instantaneous dipole- induced dipole bonds
  2. Permanent dipole- permanent dipole bonds
  3. Hydrogen bonding (strongest)
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16
Q

What intermolecular bond do all atoms and molecules form?

A

Instantaneous dipole- induced dipole bonds

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17
Q

How do instantaneous dipoles from?

A

When the electrons in an atom are more to one side than the other, forming a temporary (or instantaneous dipole).

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18
Q

How do induced dipoles form?

A

When an instantaneous dipole induces another temporary dipole in the opposite direction on a neighbouring atom

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19
Q

What occurs due to the fact that atoms are constantly moving?

A

Dipoles are constantly being created and destroyed. Even though the dipoles keep changing, the overall effect is for the atoms to be attracted to one another

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20
Q

What factors of intermolecular bonds affect the intermolecular bonds?

A

1.The shape
2.How heavy the atom or molecule is (heavier=stronger)

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21
Q

How does the length of a carbon chain effect the strength and why?

A

The longer the carbon chain, the stronger the id-id bonds because there is more molecular surface contact and more electrons to interact

22
Q

Why are branched-chain alkanes weaker?

A

They cant pack as closely together and heir molecular surface contact is smaller meaning fewer id-id bonds can form

23
Q

Why are heavier/larger molecules stronger?

A

Because they have larger electron clouds. Molecules with greater surface areas also have stronger id-id forces because they have a bigger exposed electron cloud

24
Q

What type of intermolecular bonds do polar molecules have?

A

Permanent dipole- permanent dipole

25
Why do polar molecules have pd-pd bonds?
The delta + and - charges cause weak electrostatic forces of attraction between molecules. These occur AS WELL AS id-id bonds
26
When does hydrogen bonding occur?
When hydrogen is covalently bonded to fluorine, nitrogen or oxygen
27
Why is ice less dense than water?
Water molecules in ice are arranged so there is the max number of hydrogen bonds. The lattice formed wastes a lo of space. As ice melts, some of the H bonds are broken and the lattice breaks does, allowing the molecules to fill the space
28
What do organic molecules that form H bonds contain?
-OH or -NH groups (e.g. alcohols and amines)
29
What are the two main points in collision theory?
1. The particles must collide in the right direction 2. The particles must collide with a least a certain minimum amount of kinetic energy
30
What is activation energy?
The minimum amount of kinetic energy needed to break bonds and start the reaction
31
Draw and label a Boltzmann distribution curve
Page 104 CGP book
32
How is the Boltzmann distribution curve effected by an increase in temperature?
The total number of particles remains the same so the area under the curve remains constant, but at a higher temperature, more molecules have the activation enthalpy meaning a greater proportion can react, so the curve is pushed over to the right
33
How does concentration effect the rate of reaction?
Increasing the concentration increases the rate of reaction because particles are on average closer together, meaning they'll collide more often. More collision=more chances to react
34
How does pressure effect ROR?
Increasing pressure increases the ROR because the particles are on average closer together, meaning they collide more often. More collisions=more chances to react
35
How do catalyst effect ROR?
They increase ROR by lowering the activation enthalpy by providing different ways for bonds to be broken and remade. Lower activation enthalpy=more particles have enough energy to react
36
How does temperature effect ROR?
Increasing temperature increases ROR because the particles have more energy to they are more likely to collide and react
37
What possible methods can you use to measure ROR?
1. Measure the volume of gas produced 2. Measure the loss of mass as a gas is produced 3. Measure the change in pH 4. Measure the temperature change 5. Take samples at regular intervals and analyse them by titration
38
How do you find ROR from a graph?
Draw a tangent at the time required and find the gradient. Gradient=ROR
39
What is a homogenous catalyst?
A catalyst in the same state as the reactants
40
How do catalyst increase ROR?
They provide alternative reaction pathways with a lower activation enthalpy. The catalyst is chemically unchanged at the end of the reaction
41
How to homogenous catalyst speed up ROR?
By forming one or more intermediate compounds with the reactants. The activation enthalpy needed to form the intermediates is lower than that needed to make the products directly
42
What does the enthalpy profile of a reaction sped up by a homogenous catalyst look like?
There will be two humps if the catalyst is homogeonous
43
What does the Boltzmann Distribution look like for a reaction sped up by a homogenous catalyst
The curve remains the same, but the activation enthalpy moves the left as more particales are able to react
44
What is a haloalkane?
An alkane with at least one halogen atom in place of a hydrogen
45
What occurs as you go down group 7?
The boiling points of the haloalkanes increase as you go down group 7
46
Why does the boiling point increase as you go down group 7?
The atomic radius of the halogen atoms and the number of electron shells increases, leading to stronger id-id forces between the molecules
47
What type of bond is the carbon-halogen bond in haloalkanes and why?
Polar because the electronegative halogen pulls electron density away from the carbon, making the carbon electron deficient
48
Can haloalkanes react with nucleophiles and why?
Yes because nucleophiles are electrons pair donor meaning it donates an electron pair to the carbon. OH-, NH3 and H2O are all nucleophiles that can react with haloalaknes.
49
What type of reaction do haloalkanes undergo?
Nucleophilic Substitution
50
What are the conditions for the nucleophilic substitution of haloalkanes?
Reagents: Warm aqueous sodium hydroxide Conditions: Reflux
51