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Chemistry > Bonding > Flashcards

Bonding Flashcards

1
Q

What is an ionic bond?

A

The strong electrostatic attraction between oppositely charged ions which forms a giant ionic lattice

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2
Q

Name 3 properties of an ionic bond.

A
  • High melting and boiling point
  • Electrical conductivity
  • Brittle and break easily
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3
Q

What is a metallic bond?

A

The strong electrostatic attraction between positive ions and delocalised electrons

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4
Q

Why does Mg have a higher boiling point than Na?

3 marks

A
  • Both have giant metallic lattic structure/ electrostatic attractions between + ions and delocalised electrons
  • Mg has a greater nuclear charge (2+) and more delocalised electrons
  • Mg is smaller so has greater charge density
  • Therefore stronger metallic bonds in Mg which requires more energy to break
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5
Q

Name 5 properties of a metallic bond.

A
  • Electrical conductivity
  • Thermal conductivity
  • Strong
  • Malleable+ ductile
  • High melting and boiling points
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6
Q

What is a covalent bond?

A

Shared pair of electrons between 2 atoms due to attraction between electrons and nucleus being stronger than repulsion

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7
Q

Name 2 properties of a covalent bond.

A
  • Low melting and boiling points
  • Poor conductors
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8
Q

Name the three macromolecular structures.

A
  • Carbon allotropes
  • Silicon
  • Silicon oxide
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9
Q

What is a coordinate bond?

A

A shared pair of electrons that come from the same atom

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10
Q

Decribe the bond between N in NH3 and a H+ ion.

A

N donates its lone pair of electrons to H+

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11
Q

State the shapes and bond angles of molecules with 0 lone pairs and 2, 3, 4, 5, 6 bonding pairs.

A
  • Linear: 180
  • Trigonal planar: 120
  • Tetrahedral: 109.5
  • Trigonal bipyramidal: 90 and 120
  • Octahedral: 90
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12
Q

State the shapes and bond angles of molecules with 1 lone pair and 2, 3, 4, 5 bonding pairs.

A
  • V-shape: 117.5
  • Pyramidal: 107
  • Seesaw: 119 and 89
  • Square pyramidal: 89
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13
Q

State the shapes and bond angles of molecules with 2 lone pairs and 2, 3, 4 bonding pairs.

A
  • V-shape: 104.5
  • Trigonal planar: 120
  • Square planar: 90
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14
Q

What is electronegativity?

A

The power of an atom to attract a pair of electrons in a covalent bond

Must say IN A COVALENT BOND

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15
Q

What is the most electronegative element?

A

Fluorine

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16
Q

How is a polar bond formed?

A
  • One atom is more electronegative than another
  • Causes uneven distribution of electron density (dipole)
17
Q

What is a hydrogen bond?

A
  • Strongest intermolecular attraction
  • Occurs between lone pair on F, N, O and H on another molecule
18
Q

How do hydrogen bonds arise?

A
  • Large difference in electronegativity between atom and H
  • Creates a strong dipole on bond
  • Lone pair on atom attracts H d+ on another molecule
19
Q

What types of molecules do permanent dipole-dipoles from?

A

Polar molecules

20
Q

How do permanent dipole-dipoles arise?

A
  • Difference in electronegativity between atoms on two different molecules
  • Forms dipole that doesn’t cancel out
  • d- molecule attracts d+ molecule
21
Q

What are induced dipole-dipoles?

A
  • Weakest intermolecular force
  • Occurs in non-polar molecules
22
Q

How do induced dipole-dipoles arise?

A
  • Random movement of electrons
  • Causes uneven distribution of electron density which is a temporary dipole
  • This induces a dipole in another molecule
  • d+ molecule attracts d- molecule
23
Q

Predict the shape of AlH4- ion and explain it.

(3 marks)

A
  • Tetrahedral
  • Equal repulsion
  • Between 4 bonding pairs
24
Q

Why does NaCl have a high melting point?

(3 marks)

A
  • Ionic bonds
  • Strong electrostatic forces of attraction that require lots of enery to break
  • Between Na and Cl/ oppositely charged ions
25
Q

Why does PH4+ not form hydrogen bonds?

(1 mark)

A

Difference in electronegativity is too small

26
Q

Why is the bonding in nitrogen oxide covalent and not ionic?

(1 mark)

A

Small difference in electronegativity

27
Q

In terms of IMFs why PH3 is almost insoluble in water?

(1 mark)

A

Does not form hydrogen bonds with water

28
Q

In terms of electronegativity, why is the boiling point of H2S2 lower than H2O2?

(2 marks)

A
  • Electronegativity of S is lower than O
  • Only VDWs between H2S2 molecules (no hydrogen bonds)
29
Q

Why is SbCl3 polar?

(3 marks)

A
  • Difference in electronegativity between Sb and Cl (dipole)
  • Molecule is not symmetrical
  • Dipoles do not cancel out
30
Q

Explain why the melting point of XeF4 is higher than the melting point of PF3. Give the shape of each molecule, why it has that shape and how the shape influences the forces.

A

Stage 1: e pairs
- XeF4 has 4bp and 2lp around Xe
- PF3 has 3bp and 1lp around P

Stage 2: shapes
- XeF4 is square planar
- PF3 is pyramidal- Electron pairs all repel but Lone pairs repel more than Bonding pairs

Stage 3: IMF
- XeF4 has IDDs only (symmetrical) and PF3 has PDDs
- More IMFs in XeF4
- Due to larger Mr/ more electrons/ larger molecules

Make sure to explain and compair strengths of IMFs
XeF4 is symmetrical therefore IDDs only (since dipoles cancel out)

31
Q

What is the bonding in ammonium chloride?

(1 mark)

A

Covalent, Dative and Ionic

32
Q

State the bond angle and shape in H2O and explain them

(4 marks)

A
  • V-shape
  • 104.5 degrees
  • Lone pairs repel more strongly than bonding pairs
  • So bond angle decreases from 109.5 degrees
33
Q

Explain how IDDs arise in an SiF4 molecule and why no other type of intermolecular force exists

(3 marks)

A
  • Uneven distribution of electron (density) in one molecule induces dipole in another molecule
  • Symmetrical and dipoles cancel
  • No hydrogens bonded to F so no hydrogen bonding
34
Q

Explain why sodium bromide has a higher melting point than sodium and sodium iodide

(6 marks)

A

Stage 1: Na
- Na has metallic bonding
- Attraction between positive metal ions and delocalised electrons
- Forms giant/ lattice structure

Stage 2: NaBr and NaI
- Ionic bonding in NaBr and NaI
- Electrostatic attraction between oppositely charged ions
- Forms giant/ lattice structure

Stage 3: Comparison
- Ionic bonds are stronger than metallic bonds
- There is a stronger attraction between opposite ions in NaBr than NaI
- Since Br ion is smaller than I ion

Make sure you write about Br and I ions
Make sure you write about metallic/ ionic lattices

Chemistry (12 decks)

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