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Chemistry - Unit Two > Structure, Properties and Uses of Substances > Flashcards

Structure, Properties and Uses of Substances Flashcards

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1
Q

What is the melting point of an ionic compound like?

A

High

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2
Q

What is the boiling point of an ionic compound like?

A

High

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3
Q

Why do ionic compounds have high melting and boiling points?

A

Because the ions are held together by strong electrostatic attraction which requires a lot of energy to overcome.

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4
Q

What is a useful property of melted ionic compounds?

A

They can conduct electricity.

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5
Q

Are ionic compounds soluble?

A

Yes, very.

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6
Q

What is a useful property of dissolved ionic compounds?

A

They can carry an electric current.

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7
Q

What are three characteristics of simple molecules?

A
  • Low melting and boiling points.
  • Mostly liquids or gases at room temperature.
  • Don’t conduct electricity.
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8
Q

What are the intermolecular forces between simple molecules like?

A

Very weak.

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9
Q

What are two properties of most macromolecules?

A
  • High melting and boiling point.

* Not conductive.

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10
Q

How many covalent bonds does each carbon atom in a diamond contain?

A

Four

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11
Q

What is the hardest natural substance?

A

Diamond

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12
Q

What is a use of diamond?

A

Drill tips

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13
Q

How many covalent bonds does each carbon atom in graphite make?

A

3

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14
Q

How is the carbon in graphite arranged?

A

In layers that can easily slide over each other.

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15
Q

What holds the layers in graphite together?

A

Weak intermolecular forces.

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16
Q

What happens to the extra electrons in the carbon in graphite that don’t form bonds?

A

They become delocalised which means that graphite can conduct heat and electricity.

17
Q

How does a metal’s structure affect its malleability?

A

Because the atoms are arranged in a regular structure, they can easily slide over each other which makes them easy to bend and shape.

18
Q

Why are metals conductive?

A

They have delocalised electrons that can move freely around the metal so can carry current and heat energy through the structure.

19
Q

What is an alloy?

A

Two or more metals mixed together.

20
Q

Why are alloys useful?

A

The different sized atoms disrupt the structure of the metal meaning that the layers don’t slide over each other as easily making them harder.

21
Q

What is an example of a smart material?

A

Shape memory alloys

22
Q

What are shape memory alloys?

A

A material that can be shaped but will return to its original shape when heated.

23
Q

What are two used of shape memory alloys?

A

Glasses frames and dental braces.

24
Q

What is a nanoparticle?

A

A particle between 1 and 100 manometers across.

25
Q

What is a property of silver nanoparticle a that regular silver doesn’t have?

A

They can kill bacteria.

26
Q

What are uses of nanoparticles?

A
  • Catalysts - huge surface area to volume ratio
  • Water purity tests
  • Building materials
  • Sun creams and deodorants
  • Lubricants
  • Computer chips
27
Q

What are fullerenes?

A

A type of molecule made of carbon shaped into balls or tubes. The carbon atoms are arranged in hexagonal rings.

28
Q

What are three used of fullerenes?

A
  • Lubricants and catalysts
  • Medicine
  • Reinforcing materials
29
Q

How are the polymer chains in thermosoftening polymers arranged?

A

Loose and tangled together, held together by weak intermolecular forces.

30
Q

What is a thermosoftening polymer?

A

A polymer that can be melted and shaped into a new shape.

31
Q

What is the structure of a thermosetting polymer?

A

The polymer chains are connected by cross links that hold the structure solidly in place. This means that they don’t melt, only burn.

32
Q

What are four properties of thermosetting polymers?

A
  • Strong
  • Hard
  • Rigid
  • No melting/boiling point
33
Q

How is LDPE made?

A

By heating ethene to 200 degrees under high pressure.

34
Q

What are two used of LDPE?

A

Plastic bags and bottles.

35
Q

Under what conditions is HDPE made?

A

At a low temperature and pressure in the presence of a catalyst.

36
Q

What are two used of HDPE?

A

Water tanks and drainpipes.

Chemistry - Unit Two (7 decks)

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