Intermolecular Forces Flashcards

1
Q

What is electronegativity?

A

Ability of an atom to pull electrons towards itself

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2
Q

What do atoms with a higher electronegativity do?

A

Pull electrons more strongly towards itself

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3
Q

What is periodic property?

A

Dependency on. the position of an element on the periodic table

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4
Q

What are the different types of factors which affect electronegativity?

A

Nuclear charge
Atomic radius
Electron shielding

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5
Q

What do you have to have to have a high electronegativity in terms of :
Nuclear charge
Atomic radius
Electron shielding

A

A higher nuclear charge
A small atomic radius
A low amount of shielding

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6
Q

Can you predict whether the bonding of molecules will ionic or covalent?

A

Yes by calculating the different in values of electronegativity

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7
Q

Is it more likely to be an ionic or covalent bond if the difference of electronegativity is greater than 1.7?

A

Ionic

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8
Q

Is it more likely to be an ionic or covalent bond if the difference of electronegativity is less than 1.7?

A

Covalent

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9
Q

What is the electronegativity between hydrogen and chloride?

A

0.9

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10
Q

Why is hydrogen chloride special?

A
  • In its gaseous form, hydrogen and chlorine are covalently bonded
  • In aqueous form, it ionises completely to give H+ and Cl- (Hydrochloric acid) form has a polar covalent bond
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11
Q

Finish the sentence:

If two atoms of the same element form a covalent bond, the distribution of electrons in molecular orbitals is …..

A

symmetrical

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12
Q

What happens if different atoms forms bonds?

A
  • Asymmetrical distribution of electrons in molecular orbitals
  • Different electronegativities
  • Different ability to attract electrons
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13
Q

Why is the carbon-chlorine bond polar?

A
  • Chlorine more electronegative than carbon
  • Gives an unsymmetrical bonding molecular orbital
  • Which can be illustrated with partial charges d+ and d-
  • The bond has a dipole
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14
Q

What is a permanent dipole?

A

Small charge difference across a bond that results from a difference in the electronegativities of the bonded atoms

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15
Q

Is a carbon-hydrogen bond polar or not polar?

A

Not polar

- but the molecule its self is polar and overall there is a permanent dipole

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16
Q

How can the overall dipole on a molecule be reinforced or reduced?

A

Determined by the orientation if the bonds

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17
Q

Are ionic and covalent intermolecular forces?

A

Yes

-Bonds occur between atoms

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18
Q

What is an intermolecular force?

A

Occurs between atoms

  • Difference in electronegativity values between atoms
  • Polarity of molecules
19
Q

What happens to the boiling point if you have a strong intermolecular forces?

A

High boiling point therefor high melting point

20
Q

Wha are the three types of intermolecular forces?

A
  • Dipole-dipole interactions
  • van-der Waals forces
  • Hydrogen bonds
21
Q

What are dipole-dipole reactions?

A

Molecules with a permanent dipole attack each other

-Due to electronegativity differences

22
Q

Are dipole-dipole weak or strong intermolecular forces?

A

Weak but still impact e.g boiling point

23
Q

What is required when going from liquid to vapour phase?

A

Breakage of intermolecular attractions

24
Q

How does dipole-dipole interactions affect solubility?

A

Interaction between molecules with permanent dipoles enables such compounds to dissolve

25
What are van-de Waals forces?
Interaction between molecules which do not have a permanent dipole (therefor induced dipoles)
26
How do you get van-de Waals forces?
- Electrons not beings stationary (EVEN IN SYMMETRICAL MOLECULES) - Leads to a small temporary dipole - Which induces a small temporary dipole in an adjacent molecules
27
Do larger molecules (have more electrons) have more or less temporary dipoles?
More
28
If more temporary dipoles is the attired force less or greater?
Greater
29
If the molecules are further apart are the forces stronger or weaker?
Weaker
30
What are van-her Waals forces vital in?
Maintaining lipid bilayer of a cell membrane | Protein structure
31
What are hydrogen bonding?
- Occurs when a hydrogen atom is attached to an electronegative atom, usually oxygen or nitrogen - This hydrogen atom is also attracted to another electronegative atom
32
Is hydrogen the strongest intermolecular interaction?
Yes
33
Is hydrogen bonding possible in ethanol?
Yes
34
Is hydrogen bonding possible in diethyl ether?
No
35
Does hydrogen have many vital biological roles?
Yes - complementary base pairing
36
Are protein dependent on H-bonding for structure?
Yes - enzyme substrate binding
37
Order dipole-dipole interaction, van-der Waals force and hydrogen bonding in weakest to strongest?
van-der Waals forces Dipole-dipole interaction Hydrogen bonding
38
What is solubility?
Two substances will mix completely (or a solute will dissolve in a solvent if some of intermolecular attraction between the molecules after mixing are greater than the some of intermolecular attractions before mixing
39
What is salvation?
Two compounds mixing together
40
Do compounds that show extensive hydrogen bonding dissolve in water?
Yes
41
What doe hydrocarbons really on?
Van der Waals forces for intermolecular attractions
42
Are hydrocarbons soluble in water?
No
43
If the longer the alkyl chain in water are there more or less van der Waals forces?
More causing water solubility to drop
44
Can changes in intermolecular interactions give solubility?
Yes