Chemical Bonding Flashcards

0
Q

Explain why aluminum oxide is unable to conduct electricity when solid, but able to conduct electricity when molten.

A
  1. AO is an ionic compound.
  2. When solid, ions held in fixed positions, unable to carry current.
  3. When molten, ions able to move, able to carry electric current.
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1
Q

Suggest why sodium chloride has a higher melting point than hydrogen chloride.

A
  1. SC has ionic lattice structure while HC has simple covalent structure.
  2. Greater energy required to overcome electrostatic forces of attraction in SC, compared to weaker intermolecular forces of attraction in HC.
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2
Q

Define ‘ionic bonding’.

A

Transfer of electrons from a metallic atom to a non metallic atom, in order to achieve noble gas configuration.

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3
Q

What are the steps to drawing a dot and cross diagram of an ionic compound?

A
  1. List elements present.
  2. Predict ions formed.
  3. Balance ionic charges.
  4. Draw the diagram.
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4
Q

What is covalent bonding?

A

Sharing of electrons between 2 or more non- metallic atoms, in order to achieve noble gas configuration.

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5
Q

Is hydrogen a metal or non metal?

A

Non metal.

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6
Q

Which groups do not undergo covalent bonding?

A

Groups 1,2 and 3.

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7
Q

Describe the structure of ionic lattice structure?

A

Positive and negative ions held together by strong electrostatic forces of attraction, forming a giant ionic lattice.

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8
Q

Describe the structure of simple covalent structure.

A

Small molecules loosely held together by weak intermolecular forces of attractions.

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9
Q

Describe the melting and boiling points of ionic lattice structures.

A

High melting and boiling points as large amount of energy required to overcome strong electrostatic forces between particles.

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10
Q

Describe the boiling point and melting point of simple covalent structures.

A

Low melting and boiling points, as small amount of energy required to overcome weak intermolecular forces between particles.

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11
Q

What is the solubility of ionic lattice structures?

A

Generally soluble in water, but there are many exceptions that remain insoluble eg. Silver chloride.

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12
Q

What is the solubility of simple covalent structures?

A

Generally insoluble in water, but there are many exceptions that are soluble eg. Ammonia and chlorine.

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13
Q

Describe the ability to conduct electricity in ionic lattice structures.

A
  1. Poor electrical conductivity in solid state.
  2. Good electrical conductivity in liquid or aqueous state, due to presence of mobile ions which may act as mobile charge carriers.
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14
Q

Describe the ability to conduct electricity in simple covalent structures.

A

Poor electrical conductivity in all states, due to absence of mobile charge carriers.

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15
Q

What is the strength of electrostatic forces of attraction determined by?

A
  1. Magnitude of charge

2. Physical size of ions.

16
Q

What is a metallic lattice structure?

A

Lattice of positive ions in a ‘sea’ of delocalised electrons.

17
Q

Which groups undergo metallic bonding?

A

1,2,3,4

These metals delocalize their valence electrons.

18
Q

What are the physical properties of metals?

A
  1. Moderate to high MP
  2. Good electricity conductivity when solid and molten.
  3. Insoluble in water.
  4. Malleable and ductile texture
  5. Shiny, grey appearance.
19
Q

What are some giant covalent structures?

A
  1. Macromolecule

2. Graphite

20
Q

What are 2 example of macromolecules?

A

Diamond and silicon dioxide.

21
Q

What do diamond and silicon dioxide possess?

A

Tetrahedral arrangements.

22
Q

How many molecules are found in a piece of diamond and why?

A
  1. JUST ONE

2. Since all carbon atoms are covalently joined together, entire structure considered to be one large molecule.

23
Q

Why is graphite a special substance?

A

Each carbon atom only form 3 three bonds. The last unbonded valence electron is then delocalized.

24
Q

Describe the arrangement of atoms in graphite.

A
  1. Layers of carbon atoms covalently bonded into a hexagonal arrangement
  2. Between each layer are weak intermolecular forces.
25
Q

What are some physical properties of graphite?

A
  1. Soft and slippery texture.
    - Due to weak intermolecular forces between layers of atoms, allowing layers to slider over each other easily.
  2. Good electrical conductivity
    - due to delocalized electrons present, which are mobile hence carry electric current.