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Chemistry > topic 2 - bonds, structures + properties of matter > Flashcards

topic 2 - bonds, structures + properties of matter Flashcards

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1
Q

what are the three states of matter?

A
  • solids
  • liquids
  • gases
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2
Q

describe the arrangement of solids

A
  • solids are extremely hard to compress
  • this is because the particles in a solid are packed together in a regular pattern
  • solids have a fixed shape and they cannot flow from place to place
  • this is because, in a solid, the particles can vibrate but they cannot move from place to place
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3
Q

describe the arrangement of liquids

A
  • liquids are extremely hard to compress
  • this is because the particles are close together with not many spaces between them
  • unlike solids, liquids take the shape of their container and they flow from place to place -> particles in a liquid can move
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4
Q

describe the arrangement of gases

A
  • gases are extremely easy to compress
  • this is because the particles in gases are widely spaced
  • gases spread out and fill the space of their container
  • that is because the particles in a gas move quickly and randomly
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5
Q

why do elements react?

A

to achieve a full outer energy level

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6
Q

what is an ion?

A

an atom with an overall charge

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7
Q

what is ionic bonding?

A
  • ionic bonding takes place in compounds formed from metals combined with non-metals
  • the outer electrons are transferred from the metal atom to the non-metal atom
  • ionic bonding produces ions which have the electronic structure of a noble gas
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8
Q

how are ionic compounds held together?

A
  • ionic compounds are held together in a giant lattice
  • the electrostatic forces of attraction between positive and negative ions hold the structure together
    -> these electrostatic forces are also known as ionic bonds
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9
Q

what are giant ionic lattices?

A
  • three-dimensional structures where positive ions are surrounded by negative ions
  • giant ionic lattices have very strong forces of attraction between the positive and negative ions
  • scientists call these electrostatic forces
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10
Q

what are the properties of ionic compounds?

A
  • ionic compounds have very high melting and boiling points
    -> the strong electrostatic forces require a great deal of heat energy to break
  • ionic compounds cannot conduct electricity when they are solids
    -> this is because the ions cannot move. they are locked in place by the strong electrostatic forces of attraction
  • ionic compounds can conduct electricity when they are melted or dissolved in water
    -> the ions can now move and carry the charge
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11
Q

what is a covalent bond?

A
  • a covalent bond is a shared pair of electrons between two atoms
  • this occurs between non-metals
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12
Q

what are properties of small covalent bonds?

A
  • small covalent molecules have low melting and boiling points
    -> they are usually gases or liquids at room temperature
  • small covalent molecules do not conduct electricity
    -> this is because the molecules do not have an overall electric charge
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13
Q

why do small covalent molecules have low melting/boiling points?

A
  • there are weak intermolecular forces between the molecules which do not require a lot of energy to break
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14
Q

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

A
  • as the size of the molecule increases, the intermolecular forces increases
  • this causes melting/boiling points to increase as well
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15
Q

what are the properties of giant covalent molecules?

A
  • giant covalent molecules are always solids at room temperature
  • giant covalent molecules have millions of strong covalent bonds
  • they always have high melting and boiling points
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16
Q

why are diamonds made from?

A

diamonds are formed from the element carbon
- each carbon atom forms four strong covalent bonds

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17
Q

why do diamonds have a high melting point?

A
  • each carbon atom forms four strong covalent bonds
  • diamonds have a huge number of covalent bonds and these have to be broken when the diamond is melted
18
Q

can diamonds conduct electricity?

A
  • diamonds cannot conduct electricity
  • this is because there are no free electrons to carry electrical charge
19
Q

what are the properties of graphite?

A
  • graphite has a high melting and boiling point
  • graphite is soft and slippery
  • graphite is an excellent conductor of both electricity and heat
20
Q

how is graphite formed?

A
  • graphite is formed from the element carbon
  • each carbon atom forms three covalent bonds
  • the carbon atoms form hexagonal rings
21
Q

why does graphite have a high melting point?

A
  • because graphite has many strong covalent bonds, it takes a great deal of energy to break these so graphite has a high melting and boiling point
22
Q

why is graphite slippery?

A
  • the hexagonal rings are in layers
  • there are no covalent bonds between the layers so they can slide
  • this makes graphite slippery
23
Q

why is graphite a good conductor of both electricity and heat?

A
  • only 3 out of 4 of carbon’s four outer electrons are used in bonds, so each carbon atom has one electon that’s delocalised (free)
  • delocalised electrons can move. This means they can conduct thermal energy and electricity
24
Q

what is graphene?

A
  • graphene is a single layer of graphite
  • graphene is one atom thick, making it a two-dimensional compound
25
Q

what are properties of graphene?

A
  • graphene is an excellent conductor of electricity because it has delocalised electrons
  • graphene is extremely strong
26
Q

what are fullerenes?

A
  • fullerenes are molecules of carbon atoms with hollow shapes
27
Q

how are fullerenes formed?

A
  • fullerenes are mainly made up of hexagonal rings of carbon atoms
  • however, fullerenes can also have rings of five or seven carbon atoms
28
Q

what was the first fullerene to be discovered

A
  • buckminsterfullerene was the first fullerene to be discovered
  • its got the molecular formula C60 and forms a hollow sphere
29
Q

what are uses of fullerenes?

A
  • pharmaceutical delivery
  • lubricants
  • catalysts
30
Q

what are carbon nanotubes?

A
  • nanotubes are small carbon cylinders which are formed by fullerenes
31
Q

what are properties of carbon nanotubes?

A
  • carbon nanotubes have high tensile strength (can be stretched without breaking)
  • carbon nanotubes are excellent conductors of heat and electricity
32
Q

what are uses of nanotubes?

A
  • nanotubes can be used in electronics or to strengthen materials without adding much weight, such as in tennis racket frames
32
Q

what is a molecule?

A

a group of atoms chemically bonded together

33
Q

what is a polymer?

A

millions of small molecules joined together in a chain to form a large molecule

34
Q

what is a single molecule called?

A

a monomer - monomers are often alkene molecules e.g. ethene

35
Q

what are properties of polymers?

A
  • most polymers are solids at room temperature
  • the intermolecular forces of attraction between polymer molecules are relatively strong
36
Q

describe the structure of metals

A
  • metals consist of a giant structure of atoms arranged in regular layers
  • in a metal, the electrons in the outer shell of each atom are delocalised
  • there is a strong electrostatic attraction between the sea of delocalised negative electrons and the positive metal ions
  • scientists call the electrostatic attractions in metals a metallic bond and metallic bonds are strong
37
Q

what are the properties of metals?

A
  • metals have got high melting and boiling points because a great deal of energy is required to break the strong metallic bonds
  • metals are excellent conductors of heat and electricity
  • metals are malleable
38
Q

how do metals conduct heat?

A
  • metals are excellent conductors of heat and electricity because the delocalised electrons can move
  • because electrons are charged, these moving electrons can carry an electric current
  • the moving electrons can carry thermal energy which allows metals to conduct heat
39
Q

how are metals malleable?

A
  • the layers of atoms in a metal can slide over each other
40
Q

what is an alloy?

A

a mixture of metals

41
Q

why are alloys harder than pure metals?

A
  • the different sizes of atoms distorts the layers, making it more difficult for them to slide over each other.

Chemistry (10 decks)

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