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
Q

What are van-de Waals forces?

A

Interaction between molecules which do not have a permanent dipole (therefor induced dipoles)

26
Q

How do you get van-de Waals forces?

A
  • 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
Q

Do larger molecules (have more electrons) have more or less temporary dipoles?

A

More

28
Q

If more temporary dipoles is the attired force less or greater?

A

Greater

29
Q

If the molecules are further apart are the forces stronger or weaker?

A

Weaker

30
Q

What are van-her Waals forces vital in?

A

Maintaining lipid bilayer of a cell membrane

Protein structure

31
Q

What are hydrogen bonding?

A
  • 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
Q

Is hydrogen the strongest intermolecular interaction?

A

Yes

33
Q

Is hydrogen bonding possible in ethanol?

A

Yes

34
Q

Is hydrogen bonding possible in diethyl ether?

A

No

35
Q

Does hydrogen have many vital biological roles?

A

Yes - complementary base pairing

36
Q

Are protein dependent on H-bonding for structure?

A

Yes - enzyme substrate binding

37
Q

Order dipole-dipole interaction, van-der Waals force and hydrogen bonding in weakest to strongest?

A

van-der Waals forces
Dipole-dipole interaction
Hydrogen bonding

38
Q

What is solubility?

A

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
Q

What is salvation?

A

Two compounds mixing together

40
Q

Do compounds that show extensive hydrogen bonding dissolve in water?

A

Yes

41
Q

What doe hydrocarbons really on?

A

Van der Waals forces for intermolecular attractions

42
Q

Are hydrocarbons soluble in water?

A

No

43
Q

If the longer the alkyl chain in water are there more or less van der Waals forces?

A

More causing water solubility to drop

44
Q

Can changes in intermolecular interactions give solubility?

A

Yes