bonding and structure Flashcards

1
Q

ionic bond

A

the attraction between oppositely charged ions

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2
Q

structure of an ionic compound

A

ionic lattice

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3
Q

properties of ionic compounds

A
  1. high melting and boiling points- strong ionic bonds that require a lot of energy to break
  2. cannot conduct electricity when solid, only when liquid- when solid, ions are not free to move and carry charge
    when liquid, ions are free to move and carry charge
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4
Q

ionic bonding occurs between __________________________________

A

a metal and non-metal

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5
Q

how is an ionic bond formed

A

electrons are transfered from the metal to non-metal

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6
Q

definition of a covalent bond

A

a shared pair of electrons

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7
Q

definition of a molecule

A

2 or more atoms covalently bonded together

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8
Q

definition of diatomic

A

2 atoms covelantly bonded in a molecule

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9
Q

what types of elements are present in substances which contain covalent bonds

A

non-metals

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10
Q

2 types of covelant bonds

A

simple and giant

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11
Q

why do simple covelant substances have low melting and boiling points

A

have weak van der waals’ forces between the molecules which require little energy to break

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12
Q

why are simple covelant substances poor conductors of electricity

A

thye do not have delocalised electrons that can move and carry charge

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13
Q

properties of simple covelant substances

A
  1. low melting and boiling points
  2. they are soft and brittle
  3. poor conductors of electricity
  4. insoluble in water
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14
Q

examples of giant covelant structures

A

graphite
graphene (one layer of graphite)
diamond

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15
Q

why do giant covalent structures have hight melting and boiling points

A

have strong covelant bonds which require lots of energy to break

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16
Q

definition of an allotrope

A

different forms of the same element in the same state

17
Q

in diamond each carbon atom is bonded to _____1._ other carbon atoms to form a _____2._____ structure

A
  1. 4
  2. tetrahedral
18
Q

state the properties of diamond

A
  1. high melting and boiling points
  2. poor conductors of electricity
  3. hard
19
Q

state the properties of graphite

A
  1. high melting and boiling points
  2. good conductors of electricity
  3. soft
20
Q

state the properties of graphene

A
  1. high melting and boiling points
  2. good conductors of electricity
  3. hard
21
Q

definition of a metallic bond

A

the attraction between delocalised electrons and a regular lattic of positive ions

22
Q

properties of metals

A
  1. metals often have high melting and boiling points
  2. metals are good conductors of electricity
  3. metals are malleable and ductile
23
Q

definition of malleable

A

can be hammared into shape

24
Q

definition of ductile

A

can be drawn into a wire

25
Q

why do metals usually have high melting and boiling points

A

metallic bond is strong and requires a lot of energy to break

26
Q

why are metals good conductors of electricity

A

the electrons are delocalised and are free to move and carry the charge

27
Q

why are metals malleable and ductile

A

layers (of ions) can slide over each other without disrupting the structure

28
Q

definition of an alloy

A

a mixture of elements, at least one of which is a metal

29
Q

why are alloys harder than pure metals

A

some of the ions (or atoms) in the alloy of a different size to those of the metal. this distorts the layers and makes it more difficult for the layers to slide over each other

30
Q

equation to determine the % of gold in an alloy

A

number of carats/24 x 100

31
Q

state a use of aluminium

A

overhead electrical wiring, alloys for aircraft

32
Q

state a use of copper

A

electrical wiring, plumbing, brass, coinage

33
Q

state a use of iron

A

bridges

34
Q

state a use of magnesium

A

flares, high strength, low density alloys for aircraft

35
Q

what is a nanoparticle

A

a structure that is 1-100nm in size and contains a few hundred atoms

36
Q

why do nanoparticles have different properties and uses than the bulk material

A

high surface area to volume ratio

37
Q

state a use of nanoparticles in sun cream

A

better skin coverage to the sun cream, more effective protection from u.v. rays, invisible on the skin, do not degrade on exposure to the sun

38
Q

what are the potential risks of using nanoparticles

A

cell damage, harmful effects on the enviroment