S1-L10: Metallic & Intermolecular Bonding Flashcards

1
Q

Outline and describe Ionic bonding

A
  • electrostatic attraction between two oppositely charged ions
  • strong
  • polar bond: A+ -B
  • solid at room temp
  • water soluble
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2
Q

Briefly explain what Covalent bonding is

A
  • electrostatic force between two nuclei AND shared e- pair
  • ->each atom provides equal e-‘s
  • strong
  • gases/liquids or solids at room temp
  • depends on molecule
  • can be non-polar/polarised (A-B)
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3
Q

What is Dative covalent bonding and it’s properties?

A
  • one atom provides both e-‘s in shared pair
  • ->indistinguishable from normal covalent once formed
  • strong
  • gases, liquids OR solid at room temp
  • dependent on molecule often interact with water
  • often polar (A–>B)
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4
Q

Describe metallic bonding (refer to figure 1)

A
  • electrostatic attraction between metal ions AND mobilised e-‘s
  • delocalised e-‘s not associated with particular atom
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5
Q

State the requirements for metallic bonding

A

-metal should have low

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6
Q

What are the key characteristics of metals?

A
  • great strength–>depends on n. of e-‘s AND packing of cations
  • good heat & electricity conductor in solid plus liquid state
  • malleable AND ductile
  • lustrous
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7
Q

Define “Intramolecular Forces” (figure 2)

A

-hold atoms together within molecule

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8
Q

What are “Intermolecular forces”? (figure 3)

A

-attractive forces between molecules

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9
Q

How do Intramolecular and Intermolecular forces compare?

A

-intermolecular forces much weaker than intramolecular forces

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10
Q

Outline the different intermolecular force’s types from strongest to weakest AND which ones are polar AND non-polar molecules

A
  • going strongest to weakest:
  • Ion-Dipole forces/H-bonds/ dipole-dipole forces/ Van der Waals forces
  • all states are polar molecule except Van der Waals which is non-polar
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11
Q

Describe London Dispersion forces (Van Der Waals/ London forces)
(refer to figure 4)

A
  • e-‘s constantly moving in orbitals
  • ->any given moment may be more to one side of atom/molecule than other
  • ->causes instantaneous (temporary) dipole
  • ->attraction
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12
Q

Briefly explain what Dipole-Dipole interactions are (figure 5)

A
  • relate to permanent molecular dipoles
  • ->found in bonds with electronegativity difference
  • ->molecular dipoles require non-uniform charge distribution in 3D
  • electrostatic attraction between permanent dipoles
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13
Q

What is the effect of dipole-dipole interactions and their significance?

A
  • act in addition to London (VdW) interactions
  • results in higher b. points than expected from mass of molecule
  • significance: carbonyls/protein folding
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14
Q

State what Ion-Dipole forces are and describe them (refer to figure 6)

A
  • electrostatic interaction between ion AND uncharged polar molecule
  • ->strength depends on charge on ion AND dipole’s magnitude
  • most common in solution–>like KCl in water
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15
Q

What are the conditions for Hydrogen bonding?

A
  • electronegative atom- O/N or F (delta -)
  • ->small size/high charge density/ lone e- pairs in small orbital (acceptor)
  • delta + H atom (donor) in polar bond–>usually N-H/ O-H OR F-H
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16
Q

Are there any other possible donors? (refer to figure 7)

A
  • experimental evidence exists to prove other donors in some molecules
  • ->depends on bond polarisation
17
Q

Outline and compare the structure of water and ice (figure 8)

A
  • each water molecule H-bonded to 4 others in tetrahedral formation
  • ice has diamond like structure
  • Ice: fixed arrangements of H-bonds
  • water: disorganised H-bonds break AND reform
18
Q

Boiling points of hydrides

19
Q

How is hydrogen bonding involved in DNA? (figure 10)

A

-matching n. of H bond donors and acceptors allows correct pairing of DNA bases

20
Q

Outline how hydrogen bonding is involved Alpha helix and beta structures

A
  • alpha helix AND beta sheets structures

- ->strongest interactions between amide N-H and C=O

21
Q

Why is cellulose important?

A
  • major plant cell wall component

- ->found in wood AND plant fibers/ derivatives used in textiles/ toiletries AND food products

22
Q

Describe the structure & bonding in cellulose

A
  • polymer of glucose
  • sugar chains held rigidly together by multiple H bonds within AND between chains
  • flat sheets of H-bonded chains held together by London dispersion (VdW) forces
23
Q

Outline the solubility of the following substances:

Solute–> Solvent–> IM force–> soluble

1-Sodium Chloride
2-Ehtanol
3-Hexane

A

1-Sodium Chloride–> water–> Ion-dipole–> Yes
2-Ethnaol–> water–> h-bonding–> Yes
3-Hexane–> water–> N/A–> No

24
Q

Summary of lecture

A
  • metallic bonding
  • intermolecular forces
  • -> types of I. Forces: Dispersion/ dipole-dipole/ ion-dipole/ H-bonding
  • significance of polarity-induced AND permanent
  • significance of different types of intermolecular force AND examples
25
Q

Exercise: What is the strongest intermolecular force between acetone AND water? :

dipole/ ion-dipole/ H-bonding/ London dispersion