Bonding Flashcards

1
Q

When does ionic bonding happen?

A

When a metal reacts with a non metal - oppositely charges particles

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2
Q

What is ionic bonding?

A

When the electron is transferred

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3
Q

What is the compound between a metal and non metal called?

A

An ionic compound

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4
Q

What are the properties of metals?

A
  • They conduct electricity
  • They conduct heat
  • They are malleable and ductile
  • They have high melting and boiling points
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5
Q

What energy keeps ionic bonds together?

A

Electrostatic force of attraction

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6
Q

What is covalent bonding?

A

Sharing electrons

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7
Q

Are covalent or ionic bonds stronger?

A

Ionic

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8
Q

What does covalent bonding involve?

A

Two non metals

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9
Q

Do covalent bonds have high or low melting points?

A

Low

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10
Q

How are metals structured?

A

A lattice of atoms and a sea of free electrons

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11
Q

What do thermochromic things control?

A

Temperature

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12
Q

What do photochromic things change?

A

Light

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13
Q

What can hydrogels do?

A

Absorb water

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14
Q

How big are nano particles?

A

1x10(-9)m

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15
Q

What properties does silver/silver nitrate have?

A

Antibacterial properties

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16
Q

How reactive are alkanes?

A

Not at all

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17
Q

What are the properties of an ionic compound?

A
  • A three dimensional lattice structure (giant ionic structure)
  • A high melting point
  • They conduct electricity when molten or dissolved in water
  • They’re brittle
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18
Q

How are ions in a sodium chloride crystal arranged?

A

In a cubic lattice - each ion is surrounded by six nearest neighbors of opposite charge

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19
Q

What kind of compound is water?

A

A covalent compound

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20
Q

Do covalent bonds conduct electricity?

A

Nein

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21
Q

How strong is the energy within a covalent bond?

A

Within the bond it is very strong but the molecules attract each other weakly, so they have low boiling points

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22
Q

What melting points do giant covalent compounds have?

A

High ones as atoms are held together by very strong covalent bonds

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23
Q

Give two examples of giant covalent structures

A

Diamond and graphite

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24
Q

What are diamond and graphite made out of?

A

Carbón

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25
Q

What are carbon atoms in diamond connected to?

A

Four other carbon atoms, meaning that it’s a three dimensional lattice based on a tetrahedral unit cell

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26
Q

What is graphite made of?

A

Layers of carbon atoms in hexagonal rings - bind between layers are quite weak and allow layers to slide over one and other

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27
Q

What are the properties of diamonds?

A

Transparent, an electrical insulator, very high melting point (3500 degrees) very hard

28
Q

What are the qualities of graphite?

A

Grey/black shiny solid, very soft (lubricant) also pencils, conducts electricity, high melting point (3600)

29
Q

Can graphite cells conduct electricity across layers?

A

No

30
Q

What are fullerenes?

A

Allotropes of carbon made up of balls or tubes or carbon atoms

31
Q

What are the properties of carbon nanotubes?

A

They’re very stiff and strong and have higher electrical conductivity than copper - and in a tube 10000 times thinner than a human hair

32
Q

How are carbon nanotubes formed?

A

When graphite layers form and then roll up into tubes rather than being deposited in layers

33
Q

What melting point do carbon nanotubes have?

A

A very high one

34
Q

How conductive are carbon nanotubes?

A

Very

35
Q

What are buckyballs?

A

A giant molecule of 60 carbon atoms in the shape of a ball

36
Q

What do buckyballs fit together to form?

A

A transparent yellow solid called fullerite

37
Q

What properties do buckyballs have?

A

Similar ones to nanotubes

38
Q

What is an advantage of buckyballs compared to nanotubes?

A

They can trap other molecules and therefore carry drugs to specific sites in the body

39
Q

What is graphene?

A

One layer of a graphite molecule

40
Q

What are the qualities of graphene?

A
  • The thinnest material known to man
  • The lightest material known to man
  • 100-300 times stronger than steel
  • The best conductor of heat at room temperature and the best conductor of electricity known
41
Q

Why are nano particles more useful than normal particles?

A

Because they have a much larger surface area for their size than other particles

42
Q

Why is the size of a silver nano particle particularly useful?

A

Because it can enter a living cell

43
Q

Why are some people anxious about nano particles?

A

Because some people don’t know their long term effects

44
Q

What is titanium dioxide?

A

A white solid used in house paint and coating some chocolates

45
Q

How small are titanium nano-particles

A

So small that they are invisible

46
Q

Why is titanium dioxide used in sun-cream?

A

Because it’s invisible but can block harmful ultraviolet light

47
Q

What do we have to do to titanium dioxide in suncream?

A

Coat it in something so it isn’t absorbed into the skin

48
Q

Is titanium dioxide harmful?

A

Not obviously, but some people think we don’t know enough yet

49
Q

Define smart materials

A

Materials with properties that change reversibly with a change in their surroundings

50
Q

What are most thermometric materials based on?

A

Liquid crystal technology

51
Q

What is liquid crystal technology also used in?

A

Flat screen televisions

52
Q

How do liquid crystals work?

A

At a specific temperature they re-orientate to produce a change in colour and then go back when the temperature changes

53
Q

What are thermochromic pigments used in?

A

Mugs than change colour with heat etc.

54
Q

What do photochromic pigments contain?

A

Special organic molecules that change colour when exposed to light or ultraviolet light

55
Q

What does light do to photochromic pigments?

A

It breaks a bond in the molecules, which then rearranges itself. It can return to its original form after

56
Q

What are photochromic pigments used in?

A

Photochromic lenses in glasses which allow normal glasses to become sunglasses

57
Q

What are shape-memory polymers?

A

Plastics which can regain their shape when they’re heated and then re-cooled

58
Q

What is the property in shape-memory molecules called?

A

Shape retention

59
Q

What are shape memory polymers used for in industry?

A

In the building industry for window frame sealing and manufacturing gum shields

60
Q

What are the future applications of shape-memory polymers

A

Plastic car bodies from which a dent could be removed by heating

61
Q

What’s the difference between a shape-memory polymer and shape-memory alloy?

A

The polymer is made of plastic and alloy of metal

62
Q

What are the remarkable properties of some shape-memory alloys (nickel/titanium alloys, known as NiTi)

A
  • Pseudo elasticity (they appear to be plastic)

- Shape retention

63
Q

What are the possible uses of shape-memory alloys?

A

Deformable spectacle frames, and surgical plates for joining bone fractures

64
Q

What are hydrogels?

A

Polymer gels that absorb or expel water and swell and shrink up to 1000 times their volume due to changes in pH or temperature

65
Q

How are hydrogels structured?

A

They are cross-linked to polymers that enable water and some other liquids to be absorbed within the structure, making it swell

66
Q

What do the applications of hydrogels (polymer gels) include?

A

Artificial muscles, granules added to house plant compost to retain water, filling for nappies