Chapter 3 Structure and Bonding Flashcards

1
Q

Describe the movement and arrangement of particles in a solid.

A

The particles in a solid are packed closely together and vibrate around fixed positions.

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2
Q

Describe the movement and arrangement of particles in a liquid.

A

The particles in a liquid are close together but are free to move so can move over each other.

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3
Q

Describe the movement and arrangement of particles in a gas.

A

The particles in a gas have lots of space between them and they move quickly and randomly.

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4
Q

Why do some substances have higher melting and boiling points than other substances?

A

The stronger the forces between the particles are, the more energy is required for melting or boiling. This results in higher melting and boiling points.

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5
Q

What happens at the melting point of a substance?

A

Melting and freezing take place at the melting point.

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6
Q

What happens at the boiling point of a substance?

A

Boiling and condensing take place at the boiling point.

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7
Q

What are the limitations of the simple particle model for states of matter?

A

The simple particle model has limitations. There are no forces in the model and all particles are represented as solid spheres.

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8
Q

Give the 4 state symbols and state what they stand for.

A

We use state symbols to represent the different states in chemical equations. The state symbols are:

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9
Q

What is a compound?

A

A compound is a substance made up of 2 or more elements which have chemically combined.

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10
Q

Name the 3 types of strong chemical bonds?

A

There are 3 types of strong chemical bonds: ionic, covalent and metallic.

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11
Q

Between which types of elements do ionic bonds form?

A

Ionic bonds are formed between metals and non-metals.

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12
Q

What types of ions will metal elements form?

A

Metal atoms will lose electrons to become positive ions and to have a stable full outer shell of electrons.

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13
Q

What types of ions will non-metal elements form?

A

Non-metal atoms will gain electrons to become negative ions and have a full outer shell of electrons.

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14
Q

Why would an atom gain or lose electrons?

A

Atoms will gain or lose electrons to achieve a full outer shell so they have the same electron configuration as their nearest noble gas.

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15
Q

How do ionic bonds form?

A

To form an ionic compound electron transfer takes place. Electrons move from a metal to a non-metal.

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16
Q

Name the forces that hold ions together in an ionic bond.

A

Ions are held together in ionic compounds by electrostatic forces of attraction between the positively charged metal ion and the negatively charged non-metal ion.

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17
Q

What type of diagram do we use to represent electron transfer?

A

Electron transfer during the formation of an ionic compound can be represented by a dot and cross diagram.

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18
Q

What is the overall charge on an ionic compound?

A

Ions combine so that the overall charge on the compound is zero. For example magnesium forms an ion with a charge of 2+ so will combine with 2 chloride ions that each have a charge of 1-. The formula would be Mg2+(Cl-)2

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19
Q

What makes a crystal lattice strong?

A

Ionic compounds are giant structures of ions arranged as a crystal lattice. Each ion is surrounded by oppositely charged ions in all directions making the structure very strong.

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20
Q

Why do ionic compounds have high melting and boiling points?

A

The electrostatic forces between ions in a crystal lattice are so strong that ionic compounds have very high melting and boiling points.

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21
Q

Why can ionic compounds conduct electricity when molten or when dissolved in water?

A

When melted or dissolved in water ionic compounds can conduct electricity because the ions are free to move and carry current.

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22
Q

Why are ionic compounds unable to conduct electricity when solid?

A

When solid ionic compounds are unable to conduct electricity because the ions are not free to move.

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23
Q

What types of elements form covalent bonds?.

A

Covalent bonds form between non-metals.

24
Q

How do atoms achieve a full outer shell of electrons through covalent bonding.

A

In a covalent bond non-metal atoms share pairs of electrons with other non-metal atoms to achieve a full outer shell.

25
Q

What does each shared pair of electrons represent?

A

Each shared pair of electrons represents a covalent bond.

26
Q

What forces act between small covalent molecules?

A

Weak intermolecular forces act between small covalent molecules.

27
Q

Why do small covalent molecules have low melting and boiling points?

A

Weak intermolecular forces do not require much energy to break so small covalent molecules have low melting and boiling points.

28
Q

Give 7 examples of small covalent molecules.

A

Examples of small covalent molecules include:

29
Q

Give 5 ways that we can represent covalent molecules.

A

Covalent molecules can be represented by dot and cross diagrams showing electron shells, dot and cross diagrams with no shells, displayed formula, 3D ball and stick models or 2D ball and stick models.

30
Q

Why do we need different ways to represent covalent molecules?

A

The models for representing covalently bonded molecules have limitations in representing reality.

31
Q

Why do small covalent molecules not conduct electricity?

A

Small covalent molecules do not conduct electricity as they have no charge.

32
Q

What are giant covalent structures?

A

Giant covalent structures are covalent compounds made up of huge networks of non-metal atoms.

33
Q

Give 3 examples of giant covalent molecules.

A

Examples of giant covalent structures include diamond, silicon dioxide and graphite.

34
Q

Why do giant covalent structures have very high melting and boiling points?

A

Giant covalent structures have strong covalent bonds and so have very high melting and boiling points.

35
Q

Why do giant covalent structures not conduct electricity? What is the exception to this rule?

A

Giant covalent structures do not conduct electricity because they are uncharged. The exception is graphite.

36
Q

Why is graphite soft?

A

Graphite has a unique structure with giant layers of covalently bonded carbon atoms and only weak bonds between the layers. This allows the layer to slide over each other and makes graphite soft.

37
Q

Why does graphite have delocalised electrons?

A

Carbon makes 4 bonds but in graphite each carbon is bonded to 3 more. This leaves one electron that is free to more (or delocalised).

38
Q

Why does graphite conduct electricity?

A

Graphite has delocalised electrons which means that it is capable of conducting electricity.

39
Q

What is an allotrope? What are the allotropes of carbon?

A

Allotropes are different compounds made up of the same element in the same state. Allotropes of solid carbon include graphite,diamond and fullerene.

40
Q

What are polymers?

A

Polymers are large covalent compounds made up of repeating subunits called monomers. They are often represented using only the monomer in brackets.

41
Q

Why are polymers solid at room temperature?

A

Polymers are large so have high intermolecular forces. This means they are solids at room temperature.

42
Q

Describe fullerenes.

A

Fullerenes are giant cage-like structures and tubes made of hexagonal rings of carbon.

43
Q

Give 3 uses for fullerenes.

A

Fullerenes are used as transport mechanisms for drugs, as catalysts and as reinforcements for composite materials.

44
Q

What is graphene and why is it useful in computer chips?.

A

Graphene is a single layer of graphite and is one atom thick and is being used to make more powerful computer chips due to its small size and ability to conduct electricity.

45
Q

How are atoms in metals arranged?.

A

Atoms in metals are arranged in regular layers so they form giant structures called metallic crystals.

46
Q

Describe the arrangement of ions and electrons in metals.

A

Due to the arrangement of metal atoms the outer electrons become delocalised resulting in positive metal atoms in a sea of electrons.

47
Q

Why are metals able to conduct electricity and thermal energy?

A

Metals are able to conduct electricity and thermal energy due to their delocalised electrons.

48
Q

What does malleable mean?

A

Metals are malleable. This means they can be hammered into different shapes. This is due to the layers of atoms that can slip past each other.

49
Q

What does ductile mean?

A

Metals are ductile. This means they can be drawn into wires. This is also due to the layer that can slip past each other.

50
Q

What are alloys?

A

Alloys are mixtures of metals or metals and carbon (as in steel).

51
Q

Why are alloys harder than metals?

A

Alloys are harder than metals because the mixture of different sized metal ions disrupts the regular layers.

52
Q

What is nanoscience? (TRIPLE ONLY)

A

Nanoscience is the study of small particles that are between 1 and 100 nanometres in size.

53
Q

What is special about nanoparticles?
(TRIPLE ONLY)

A

Nanoparticles have a high surface area to volume ratio with a high proportion of their atoms exposed at their surface.

54
Q

Why are nanoparticles used as catalysts?
(TRIPLE ONLY)

A

Nanoparticles can be used as catalysts in much smaller quantities due to their properties.

55
Q

Give 3 potential future uses of nanoparticles.
(TRIPLE ONLY)

A

Nanoparticles have many future applications such as use in sensors, in wires or in new fabrics.

56
Q

What are the risks associated with nanoparticles?
(TRIPLE ONLY)

A

Nanoparticles come with risks. We still do not know the issues that may arise in terms of health or environment.