4.5 Metallic bonding Flashcards

(25 cards)

1
Q

Why are metals good conductors of heat and electricity?

A

Metallic ions have a sea of delocalized electrons which allow heat and electricity to be conducted

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2
Q

How are metal ions arranged?

A

Cations are arranged in a lattice structure

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3
Q

Metallic bond

A

Electrostatic attraction between lattice of positive metal ions and sea of delocalized electrons

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4
Q

Why is the force of attraction between metallic ions non-directional?

A

Because the force of attraction is in all directions. The electrons don’t “belong” to any atom

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5
Q

Why are metals malleable and ductile?

A

If sufficient force is applied, one layer of metal can slide over another without disrupting bond

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6
Q

How do metals pass electricity?

A

When voltage is applied, electrons are repelled from negative electrode and move towards positive electrode. This constitutes flow of an electric current

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7
Q

How is heat passed through metals?

A

Electrons move, carrying kinetic energy from hotter parts to colder parts of the metal

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8
Q

How do metals get their shininess?

A

Electrons reflect wavelengths of visible light

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9
Q

What does strength of bond depend on?

A
  1. Charge on metal ion

2. Ionic radius of ion

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10
Q

What can be used as an approximate measure for bond strength?

A

Melting point. Stronger bond = higher M.P.

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11
Q

Which has stronger metallic bond and explain why:

  • K (1+, ionic radius of 138 and melting point of 63.4C)
  • Ca (2+, ionic radius of 100 and melting point of 842C)
A

Calcium because:

  • Higher ionic charge= more delocalized electrons which increases forces of attraction
  • Smaller radius means more attraction between nuclei and electrons
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12
Q

How does ionic radius affect density of metals?

A

Decrease in radius means higher charge and hence higher density

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13
Q

Alloys

A

Homogenous mixtures composed of two or more metals or a metal and a non-metal

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14
Q

How do properties of alloys differ from those of pure metals?

A
  • More corrosion-resistant
  • Stronger
  • Harder
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15
Q

What state do metals have to be in to make alloys?

A

Molten so that atoms can mix

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16
Q

Why are alloys hard?

A

Because there is addition of different sized atoms which means they cannot slide over each other

17
Q

Are alloys more or less chemically stable than metals?

A

More chemically stable

18
Q

Composition, properties and use of brass

A
  • 70% copper and 30% zinc
  • Harder than copper
  • Used for musical instruments
19
Q

Composition, properties and use of bronze

A
  • 90% copper and 10% tin
  • Harder than copper
  • Used to make statues
20
Q

Composition, properties and use of stainless steel

A
  • 74% iron, 18% chromium, 8% nickel
  • More resistant to corrosion
  • Used in cutlery
21
Q

Composition, properties and use of mild steel

A
  • 99.7% iron and 0.3% carbon
  • Stronger and harder than iron
  • Used in construction
22
Q

Composition, properties and use of solder

A
  • 50% tin and 50% lead
  • Lower melting points
  • Used in electric circuit boards
23
Q

Which has stronger London dispersion forces: C3H8 or C4H10?

A

C4H10 because it has higher molar mass so it has stronger forces

24
Q

Which has stronger intermolecular forces: C3H8 or C2H4O?

A

C2H4O because even though they have same molar mass, C3H8 is non-polar while C2H4O is polar hence it can form dipole-dipole forces which are stronger

25
Why does Mg have 6X higher melting point than Na?
1. Double the delocalized electrons 2. Charge on cations is double so more attraction 3. Ionic radius is smaller so charge density is more