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[GCSE] chemistry > C2: Bonding, structure and the properties of matter > Flashcards

C2: Bonding, structure and the properties of matter Flashcards

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1
Q

define ionic bonding

A
  • bonding involving the electrostatic attraction between positive and negative ions
  • it is a relatively strong attraction
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2
Q

give two ways ionic compounds are held together

A
  • held together in a giant lattice
  • electrostatic attraction between positive and negative ions
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3
Q

state 3 properties of ionic substances

A
  • high melting and boiling point ( strong electrostatic forces between oppositely charged ions)
  • do not conduct electricity when solid ( ions in fixed positions)
  • do conduct when molten or dissolved in water- ions are free to move
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4
Q

how are ionic compounds formed? Explain in terms of MgO case

A
  • reaction of a metal with a non-metal
  • electron transfer occurs ; metal gives away its outer shell electrons to non-metal
  • Mg is in group 2 so has 2 outer shell electrons
  • O is in group 6 so accepts 2 electrons to get a full outer shell configuration
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5
Q

what is a covalent bond?

A
  • a shared pair of electrons between two atoms
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6
Q

Describe the structure and properties of simple molecular covalent substances (4)

A
  • do not conduct electricity ( no ions)
  • small molecules
  • weak intermolecular forces thus:
  • low melting and boiling points
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7
Q

how do intermolecular forces change as the mass/size of the molecules increases?

A
  • they increase
  • that causes melting/boiling points to increase as more energy is needed to overcome these forces
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8
Q

define polymer

A
  • polymers are very large molecules with atoms linked by covalent bonds
  • made up of repeating subunits known as monomers
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9
Q

what are thermosoftening polymers?

A
  • special type of polymers that melt/soften when heated.
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10
Q

give three properties of thermosoftening polymers

A
  • there are no bonds between polymer chains.
  • strong intermolecular forces ensure that the structure is solid at room temperature
  • these forces are overcome with heating - polymer melts
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11
Q

what are giant covalent substances?
- give two characteristics
- give 3 examples

A
  • solids where atoms are covalently bonded together in a giant lattice
  • high melting/boiling points - strong covalent bonds
  • mostly don’t conduct electricity ( no delocalised e-)
  • eg, diamond, graphite, silicon dioxide
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12
Q

define an allotrope and give the 5 allotropes of carbon

A
  • different structural forms of an element
  • diamond, graphite, fullerenes, nanotubes, graphene
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13
Q

describe the structure of diamond

A
  • four, strong covalent bonds for each carbon atom
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14
Q

give 3 properties of diamond

A
  • very hard (strong bonds)
  • very high melting point ( strong bonds0
  • does not conduct ( no delocalised electrons)
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15
Q

describe the structure of graphite

A
  • three covalent bonds for each carbon atom
  • layers of hexagonal rings
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16
Q

Give 4 properties of graphite

A
  • high melting point due to strong covalent bonds
  • layers free to slide as weak intermolecular forces between layers
  • soft and so can be used as a lubricant
  • conduct thermal and electricity due to one delocalised electron per each carbon atom
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17
Q

describe the structure of a fullerene and give an example

A
  • hollow shaped molecules
  • based on hexagonal rings but may have 5-7 carbon rings
  • C60 has spherical shape, simple molecular structure called ‘ Buckminsterfullerene’
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18
Q

Give three properties of a fullerene

A
  • high tensile strength
  • high electrical and heat conductivity
  • high ductility
19
Q

describe the structure of nanotubes

A
  • cylindrical fullerene with high length to diameter ratio
20
Q

give two properties of nanotubes

A
  • high tensile strength ( strong bonds)
  • conductivity ( delocalised electrons)
21
Q

what is graphene?

A
  • a single layer of graphite
22
Q

what is metallic bonding?

A
  • forces of attraction between delocalised electrons and nuclei of metal ions
23
Q

give three properties of metallic structures

A
  • high melting /boiling points ( strong forces of attraction)
  • good conductor of heat and electricity (delocalised) electrons
  • malleable, soft ( layers of atoms can slide each other whilst maintaining the attraction forces)
24
Q

why are they harder then pure metals ?

A
  • different sizes of atoms distorts the layers
  • so they can’t slide over each other
  • alloys are harder than pure metals
25
Q

what are alloys?

A
  • mixtures of metal with other elements, usually metals
26
Q

describe a simple covalent structure:

A
  • low boiling and melting points due to weak intermolecular forces between molecules
  • poor conductivity when solid as no ions to conduct
  • poor when molten no ions
  • mostly seen in gases and liquids
27
Q

describe a ionic structure : include
- boiling and melting points
- conductivity when solid and when molten
- general description

A
  • high because of giant lattice of ions with strong forces between oppositely charged ions
  • poor : ions can’t move
  • good: ions are free to move
  • crystalline solids
28
Q

describe a giant covalent structure: include
- boiling and melting points
- conductivity when solid and when molten
- general description

A
  • high because of many strong covalent bonds between atoms in giant structure
  • diamond and sand: poor because electrons can’t move; graphite : good as free delocalised electrons between layers can move through structure
  • conductivity when molten: poor
    general description: solids
29
Q

describe a metallic structure: include
- boiling and melting points
- conductivity when solid and when molten
- general description
(CAN BE USED FOR A GENERAL METAL EG MAGNESIUM)

A
  • high - strong electrostatic forces between positive ions and delocalised electrons
  • good: delocalised electrons are free to move through structure
  • good
  • shiny metal solids
30
Q

give two limitations of three dimnesional and two dimensinal models

A

2D
- do not give accurate information on the shape of molecule
- only shows one layer

31
Q

give 2 benefit and two limitations of a ball and stick diagram

A
  • can see ions in 3 dimensions
    cons:
  • unable to tell which electron in the bond came from which atom
  • do not show outer electrons in the bond
32
Q

give two limitations of the dot and cross diagrams

A
  • do not tell us the shape of the molecule
  • how the ions are arranged in space
33
Q

what are limitations of the simple model?

A
  • there are no forces illustrated between spheres and atoms, molecules and ions re solid spheres- this is not true
34
Q

what does the amount of energy needed to change state from solid to liquid or liquid to gas depend on

A
  • the strength of the forces between the particles of the substance
  • the nature of the particles involved depends on the type of bonding and structure of the substance
  • the stronger the forces between the particles the higher the melting point and boiling point of the substances
35
Q

when will a pure substance melt or boil at?

A
  • a fixed temperature
  • a mixture will melt over a range of temperatures
36
Q

give the three states of matter

A

solid
liquid
gas

37
Q

what is nanoscience?

A
  • science that studies particles that are 1-100nm in size
38
Q

state 5 uses of nanoparticles

A
  • medicine ( drug delivery systems)
  • electronics
  • deodorants
  • sun creams ( better kin coverage and more effective protection against cell damage)
  • catalysts
39
Q

what are fine and coarse particles?
- give the diameter range

A

fine particles ( soot) ; 1 x 10-7 m and 2.5 x 10-6 m diameter
coarse particles ( dust); 1 x 10- 5 m and 2.5 x 10- 6 m

40
Q

why do nanoparticles have properties different from those for the same materials in bulk

A
  • high surface area to volume ratio
41
Q

What shape are
nanoparticles
approximated to?

A

a cube

42
Q

What happens to the
surface area to volume
ratio of a cube if you
decrease the side of a
cube by a factor of 10?

A

The SA:V ratio increases by a factor of 10

43
Q

. Why are
nanoparticles used
instead of the same
material in bulk?

A

less needed for the same effect

44
Q

give 5 uses for fullerenes

A
  • drug delivery (round the body)
  • hydrogen storage
  • anti-oxidants
  • reduction of bacterial growth
  • catalysts

[GCSE] chemistry (12 decks)

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