Covalent bonding Flashcards

1
Q

What is a covalent bond?

A

Strong electrostatic attraction between a shared pair of electrons and the positive nuclei

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2
Q

What type of elements form covalent bonds?

A

non-metals

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3
Q

Give the displayed formula of H₂O

A

H-O-H

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4
Q

Give the displayed formula of O₂

A

O=O

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5
Q

What is a single covalent bond

A

single pair

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6
Q

What is a double covalent bond?

A

two pairs

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7
Q

What is a simple molecular substance?

A

A simple molecular substance is a covalent molecule made up of just a few atoms

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8
Q

What is the melting point of a simple molecular substance and why?

A

low because weak intermolecular forces do not require a lot of energy to overcome

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9
Q

What is the conductivity of a simple molecular substance?

A

do not conduct electricity as no ions or delocalised electrons that can move

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10
Q

What is the solubility of a simple molecular substance?

A

usually insoluble in water as simple molecules are not attracted to water

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11
Q

What is a Buckminster fullerene?

A

(C₆₀) simple molecule composed of 60 carbon atoms in a ball

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12
Q

What is the boiling point in a Buckminster fullerene?

A

600ºC
low compared with giant covalent structures due to weak intermolecular forces which don’t require a lot of energy to overcome
high compared with other simple molecular substances as there are more electrons in the molecule

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13
Q

Why is a Buckminster fullerene soft and slippery?

A

weak intermolecular forces that can move

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14
Q

What is a giant covalent substance?

A

Structures containing a large number of non-metal atoms each joined to adjacent atoms by covalent bonds.

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15
Q

Give three examples of giant covalent substances

A

Diamond (each carbon atom bonded to 4 others), silicon dioxide, graphite (each carbon atom bonded to 3 others)

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16
Q

What type of melting point do giant covalent structures have and why?

A

High as lots of energy is needed to break strong covalent bonds

17
Q

What is the conductivity of a giant covalent substance and why?

A

usually non-conductive as no free ions and delocalised electrons that can move

18
Q

What are the properties of Diamond and Silicon Dioxide?

A

Hard - strong covalent bonds require lots of energy to break
High melting point - lots of energy required to break strong covalent bonds
Insoluble
cannot conduct electricity - no free ions and delocalised electrons that can move

19
Q

Uses of diamond?

A

diamond tipped drill bits, cutting tools

20
Q

What are the properties of graphite?

A

high melting point - lots of energy needed to break strong covalent bonds
soft - layers can slide over each other due weak forces between them
conductive - each carbon atom has a spare electron that is delocalised and can move

21
Q

Uses of graphite?

A

pencils

22
Q

What are the allotropes of carbon?

A

diamond, graphite, Buckminster fullerene

23
Q

What is a metallic bond?

A

a strong electrostatic attraction between positive metal ions and delocalised electrons

24
Q

What type of melting point do metallic compounds have and why?

A

high as has strong bonds that require lots of energy to overcome

25
Q

What is the conductivity of metallic compounds have and why?

A

Conducts electricity as ions are free to move

26
Q

Why are metallic compounds malleable?

A

rows can slide over eachother

27
Q

What type of structure do ionic compounds form?

A

giant ionic lattice

28
Q

What is an ionic bond?

A

a strong electrostatic attraction between positive and negative ions

29
Q

What type of melting point do ionic compounds have and why?

A

high due to strong electrostatic attraction between positive and negative ions that takes lots of energy to overcome

30
Q

What is the conductivity of ionic compounds have and why?

A

non-conductive when solid as ions are not free to move
conductive when molten or in a solution as ions are free to move

31
Q

Why are ionic compounds brittle?

A

Force moves ions causing them to repel from each other and break apart