3.1.3 Bonding Flashcards

1
Q

Name the 4 types of crystal structure.

A
  • Simple molecular
  • Ionic
  • Metallic
  • Macromolecular
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2
Q

Give examples of macromolecular crystal structures.

A
  • Silicon dioxide
  • Diamond
  • Graphite
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3
Q

What is a covalent bond?

A

Shared pair of electrons between two non-metals

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4
Q

What is a dative covalent bond?

A

When both electrons in a covalent bond are donated from one atom

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5
Q

What is a metallic bond?

A

Strong electrostatic attraction between the positive metal ions and delocalised electrons

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6
Q

Why can metallic compounds conduct electricity?

A
  • Sea of delocalised electrons and positive metal ions.
  • Delocalised electrons are free to flow and carry charge
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7
Q

Why are metallic compounds malleable?

A
  • Layers of positive metal ions able to slide over eachother
  • Layers don’t repel because of delocalised electrons
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8
Q

What are the factors that affect the strength of metallic bonds?

A
  • Metal charge on ion (determines number of delocalised electrons per ion)
  • Ionic radius on cation
    (nuclear charge + shielding)
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9
Q

What is an ionic bond?

A

Strong electrostatic attraction between oppositely chagred ions.

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10
Q

Why can ionic compounds conduct electricity when molten/liquid state and not as a solid?

A
  • Ions are free to move and carry charge when molten/liquid
  • When solid, ions not free to move and carry charge
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11
Q

Why are ionic compounds hard and brittle?

A
  • When layers slide over eachother the like charged ions repel eachother
  • Layers repel and the structure breaks
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12
Q

What does the strength of an ionic bond depend on?

A
  • Ionic charge
  • Ionic radius
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13
Q

Shape and bond angle for the following molecules:
a) 2 bonding pairs
b) 3 bonding pairs
c) 2 bonding pairs + 1 lone pair

A

a) Linear, 180°
b) Trigonal planar, 120°
c) V-shaped, 118°

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14
Q

Shape and bond angle for the following 4 electron pair molecules:
a) 4 bonding pairs
b) 4 bonding pairs + 1 lone pair
c) 4 bonding pairs + 2 lone pair

A

a) Tetrehedral, 109°
b) Trigonal pyramidal 107°
c) V-shaped, 105°

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15
Q

Shape and bond angle for the following 5 electron pair molecules:
a) 5 bonding pairs
b) 4 bonding pairs + 1 lone pair
c) 3 bonding pairs + 2 lone pair

A

a) Trigonal bipyramid, 90° and 120°
b) no name, 119° and 89°
c) T-shape, 89°

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16
Q

Shape and bond angle for the following molecules:
a) 6 bonding pairs
b) 5 bonding pairs + 1 lone pair
c) 4 bonding pairs + 2 lone pair

A

a) Octhedral, 90°
b) Distorted square pyramid, 89°
c) Square planar, 90°

17
Q

In terms of electron pairs, explain why the bond angles in a NH4+ ion are all 109°?

A
  • 4 bonding pairs of electron
  • All equally repel eachother as far apart as possible
  • Creating a tetrehdral shape with 109° bond angles
18
Q

What are the 3 types of IMFs?

A
  1. Hydgrogen bonds
  2. Permanent dipole-dipole interactions
  3. Van der Waals’ forces
19
Q

What controls the strength of Van der Waals’?

A

Nuclear charge and number of electrons

20
Q

What IMF is present in a molecule of SiF4? Why are no other IMFs present?

A
  • Van der Waals’
  • No H-bonds due to lack of electronegativty difference
  • No permant dipole-dipole interactions as molecule is symetrical, dipoles cancel
21
Q

Give the meaning of the term electronegativity?

A

The ability of an atom to attract a bonding pair of electrons towards itself in a covalent bond

22
Q

Why does electronegativity increase from left to right across a period?

A
  • Similar shielding
  • Increased nuclear charge
  • Smaller atomic radius
23
Q

Why is an O-H bond in a molecule polar?

A
  • Oxygen has high electronegativity
  • Hydrogen has lower
  • Oxygen atom attracts electron density
24
Q

Explain how the strongest type of IMF in liquid HF arises.

A
  • Large difference in electronegativity between hydrogen and fluorine, polar H-F bond
  • Dipole: partially positive hydrogen, partially negative fluorine
  • Partially positive hydrogen attracts to lone pair of electrons on fluroine
25
Q

Why does boiling point of hydrogen halides increase from HCl to HI?

A
  • Nuclear charge increases, more electrons present as you go down group
  • Strong Van der Waals’
  • Requires more energy to overcome
26
Q

Why is the boiling point of HF the highest for all the hydrogen halides?

A
  • Only one with hydrgoen bonds
  • Stronger IMF that requires more energy to overcome