c2 - bonding Flashcards

1
Q

what is ionic bonding?

A

when a metal reacts with a non-metal, this is ionic bonding
electrons are transferred

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2
Q

what happens when electrons are lost?

A

a positively charged ion is formed.

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3
Q

what happens when electrons are gained?

A

a negatively charged ion is formed

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4
Q

what holds ions together in a giant ionic lattice (+ and - arrangement)

A

electrostatic forces of attraction

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5
Q

what melting and boiling points do ionic compounds have?

A

Ionic compounds have very high melting and boiling points

Why?

The strong electrostatic forces require a lot of energy to break

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6
Q

can ionic compounds conduct electricity when their solid

A

Ionic compounds CANNOT conduct electricity when they are SOLID

Why?

This is because the ions cannot move (they are locked in place by the strong electrostatic forces of attraction)

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7
Q

what do we do to ionic compounds so they can conduct electricity?

A

They CAN CONDUCT ELECTRICITY when they are MELTED or DISSOLVED IN WATER

Why?

The ions are free to move and carry the charge

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8
Q

what does covalent bonding take place in

A

Covalent bonding takes place between non-metal
elements

A covalent bond is a shared pair of electrons

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9
Q

what are small covalent molecules at room temperature?

A

usually gases or liquids at room temperature

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10
Q

what melting and boiling point do small covalent bonds have?

A

low melting and boiling points

they do not conduct electricity

because they have weak forces between the molecules called intermolecular that are easy to overcome

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11
Q

what are giant covalent structures at room temperature

A

solid

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12
Q

what melting and boiling point do giant covalent bonds have

A

high melting and boiling points

why?
a lot of energy is needed to break the bonds

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13
Q

what is diamond made from?

A

Made from carbon

Each carbon atom forms 4 strong covalent bonds

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14
Q

can diamond conduct electricity?

A

it cannot conduct electricity

no free electrons to carry the charge

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15
Q

what is silica?

A

giant covalent structure
it has 4 strong covalent bonds

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16
Q

what melting and boiling point does silica have?

A

it has a high melting and boiling point because it needs a lot of energy to overcome the bonds

17
Q

describe graphite

A

Giant covalent structure

Each carbon atom forms 3 covalent bonds

The carbon atoms form hexagonal rings

18
Q

what are the properties of silica

A

Graphite is soft and slippery

Why?

It has layers that can slide over each other

Has a very high melting and boiling point

Why?

a lot of energy is needed to break the bonds

Graphite is an excellent conductor of both electricity and heat

Why?

delocalised electrons which can move between the layers

19
Q

describe graphene

A

Graphene is a single layer of graphite

It is one atom thick

It is extremely strong

It is an excellent conductor of electricity BECAUSE IT HAS
DELOCALISED ELECTRONS

20
Q

what are fullerenes?

A

Fullerenes are molecules of carbon atoms with HALLOW shapes

Usually, fullerenes have hexagonal rings of carbon atoms

1st fullerene to be discovered: Buckminsterfullerene (C^60)

21
Q

what are the uses for fullerenes?

A

Uses:

  • Pharmaceutical delivery
  • Lubricants
  • Catalysts
22
Q

what are the uses of carbon nanotubes?

A

Fullerenes shaped into long cylinders

Uses:

  • High tensile strength (can be stretched without breaking)
  • Excellent conductors of heat and electricity
  • Used to reinforce materials e.g. tennis rackets
23
Q

What are polymers?

A

Polymers are made by joining together thousands of small,
identical molecules (monomers)

Monomers are often alkene molecules e.g. ethene

24
Q

what are the properties of polymers?

A

Most polymers are solid at room temperare

The intermolecular forces of attraction between polymer
molecules are relatively strong so a lot of energy is needed to
break the bonds

25
Q

describe metallic bonding

A

Metals consist of a giant structure of atoms arranged in regular
layers

The electrons in the outer energy level of each atom are
delocalised

26
Q

what are the properties of metals

A

Metals can be bent and shaped
Why?
The layers of atoms are able to slide over each other

Metals have a high melting and boiling point
Why?
A lot of energy is needed to break the strong metallic bonds

Metals are excellent conductors of heat and electricity
Why?
The delocalised electrons can move and carry current

27
Q

examples of pure metals

A

gold
copper
iron

They are not hard enough to be useful so we make alloys

28
Q

what are alloys?

A

An alloy is a mixture of metals

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

Alloys are harder than pure metals

29
Q

Advantages and disadvantage of dot and cross diagram

A

advantage:
It is very clear where the electrons are coming from

disadvantage:
Do NOT tell us about the shape of the molecule

30
Q

disadvantage of 2D stick diagram

A

disadvantage:
The covalent bond is shown as a stick - we can’t tell which electron in the bond came from which atom
No idea of outer electrons that are not in bonds
Do NOT give us accurate information on the shape of the molecule

31
Q

advantage of 3D stick diagram

A

Shows the shape of the molecule

32
Q

advantages and disadvantages of ball and stick diagram

A

advantage:
allows us to see the ions in 3 dimensions clearly

disadvantage:
in the diagram it shows the ions are widely spaced out when in reality they are packed together
- The model isn’t to scale: so the relative sizes of the ions are not shown
- In reality, there are no gaps between the ions

33
Q

advantages and disadvantages of space-filling diagram

A

advantage:
gives us a better idea of how closely packed the ions are

disadvantages:
difficult to see the three-dimensional packing
Only shows the outer layer