C3- Structure and Bonding Flashcards

1
Q
  1. State the three types of strong chemical bonds.
A

Ionic, covalent and metallic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q
  1. In ionic bonds, what are the bonds formed between?
A

For ionic bonding the particles are oppositely charged ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q
  1. In covalent bonding, what are the bonds formed between?
A

For covalent bonding the particles are atoms which share pairs of electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  1. In metallic bonding, what are the bonds formed between?
A

For metallic bonding the particles are atoms which share delocalised electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  1. Between which classes of elements do ionic bonds form?
A

Ionic bonding occurs in compounds formed from metals combined with non-metals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. Between which classes of elements do covalent bonds form?
A

Covalent bonding occurs in non-metallic elements and in compounds of non-metals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  1. Between which classes of elements do metallic bonds form?
A

Metallic bonding occurs in metallic elements and alloys.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. How does an ionic bond form?
A
  • When a metal atom reacts with a non-metal atom electrons in the outer shell of the metal atom are transferred.
  • Metal atoms lose electrons to become positively charged ions.
  • Non-metal atoms gain electrons to become negatively charged ions.
  • The ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 have the electronic structure of a noble gas (Group 0).
  • The ionic bond is the result of the strong electrostatic attraction between the oppositely charged ions.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  1. Describe the characteristics of an ionic structure.
A
  • An ionic compound is a giant structure of ions.
  • Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.
  • The forces act in all directions in the lattice and this is called ionic bonding.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  1. Describe the characteristics of a covalent molecule or structure.
A
  • When atoms share pairs of electrons, they form covalent bonds.
  • These bonds between atoms are strong.
  • Covalently bonded substances may consist of small molecules, such as H2, Cl2, O2, N2, HCl, H2O, NH3 and CH4.
  • Some covalently bonded substances have very large molecules, such as polymers.
  • Some covalently bonded substances have giant covalent structures, such as diamond and silicon dioxide.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. Describe the characteristics of a metallic structure.
A
  • Metals consist of giant structures of atoms arranged in a regular pattern.
  • The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
  • The sharing of delocalised electrons gives rise to strong metallic bonds.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  1. State the three states of matter
A

The three states of matter are solid, liquid and gas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  1. What are the transitions between states and where do they occur?
A

Melting and freezing take place at the melting point, boiling and condensing take place at the boiling point.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  1. What is the model that represents the three states of matter?
A

The particle model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  1. How does the particle model represent the three states of matter?
A
  • In this model, particles are represented by small solid spheres.
  • In solids, they are in a close packed, regular arrangement
  • In liquids they are in a close packed, random arrangement.
  • In gases, the particles are separate from each other.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  1. How is particle theory used to explain melting, boiling, freezing and condensing?
A
  • The amount of energy needed to change state from solid to liquid and from liquid to gas depends on the strength of the forces between the particles of the substance.
  • The nature of the particles involved depends on the type of bonding and the structure of the substance.
  • The stronger the forces between the particles the higher the melting point and boiling point of the substance.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q
  1. What are the limitations of the particle model?
A

Limitations of the simple model include that there are no forces between the spheres, that all particles are represented as spheres and that the spheres are solid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q
  1. How are the states of matter represented in a chemical equation?
A

In chemical equations, the three states of matter are shown as (s), (l) and (g), with (aq) for aqueous solutions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q
  1. Why do ionic structures have high melting and boiling points?
A

These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds.

20
Q
  1. Why do ionic compounds conduct electricity when molten or in aqueous solution?
A

When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.

21
Q
  1. Why do simple covalent structures have low melting and boiling points?
A
  • Substances that consist of small molecules are usually gases or liquids.
  • These substances have only weak forces between the molecules (intermolecular forces).
  • It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or boils.
  • The intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points.
22
Q
  1. Why do simple covalent compounds not conduct electricity?
A

These substances do not conduct electricity because the molecules do not have an overall electric charge.

23
Q
  1. What is a polymer?
A

Polymers are very large molecules where the atoms in the polymer are linked to other atoms by strong covalent bonds.

24
Q
  1. Why are polymers solid at room temperature?
A

The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature.

25
Q
  1. Why do giant covalent structures have high melting and boiling points?
A

All of the atoms in these structures are linked to other atoms by strong covalent bonds. These bonds must be overcome to melt or boil these substances. Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples of giant covalent structures.

26
Q
  1. Why do most metals have high melting and boiling points?
A

Metals have giant structures of atoms with strong metallic bonding. The strong forces are difficult to overcome, so the melting and boiling points are high.

27
Q
  1. Why are metals malleable (bendable) and ductile (can be drawn into wires)?
A

In metals, the layers of atoms are able to slide over each other. This means metals can be bent and shaped.

28
Q
  1. What is an alloy?
A

An alloy is a mixture of two or more metals.

29
Q
  1. Why are most metals in everyday use alloyed?
A

Metals such as pure copper, gold, iron and aluminium are too soft for many uses and so are mixed with other metals to make alloys.

30
Q
  1. How does mixing two metals in an alloy make them harder?
A

The different sizes of atoms in an alloy distort the layers in the structure, making it more difficult for them to slide over each other, so alloys are harder than pure metals.

31
Q
  1. Why are metals good conductors of electricity?
A

Metals are good conductors of electricity because the delocalised electrons in the metal carry electrical charge through the metal.

32
Q
  1. Why are metals good thermal (heat) conductors?
A

Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.

33
Q
  1. Describe the structure of diamond.
A

In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.

34
Q
  1. Describe the structure of graphite.
A
  • In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings and so graphite has a high melting point.
  • The layers are free to slide over each other because there are no covalent bonds between the layers and so graphite is soft and slippery.
  • In graphite, one electron from each carbon atom is delocalised. These delocalised electrons allow graphite to conduct thermal energy and electricity
35
Q
  1. What is graphene?
A

Graphene is a single layer of graphite and so is one atom thick.

36
Q
  1. What are Fullerenes?
A

Fullerenes are molecules of carbon atoms with hollow shapes.

37
Q
  1. Describe the structure of Fullerenes.
A

The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms.

38
Q
  1. What was the first Fullerene to be discovered?
A

The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape.

39
Q
  1. What are carbon nanotubes?
A

Carbon nanotubes are cylindrical fullerenes. They have high tensile strength, high electrical conductivity and high thermal conductivity.

40
Q
  1. What are the uses of Fullerenes?
A

Fullerenes can be used for drug delivery into the body, as lubricants, as catalysts and carbon nanotubes can be used for reinforcing materials, e.g. in tennis rackets.

41
Q
  1. What is nanoscience?
A

Nanoscience refers to structures that are 1–100 nm in size, of the order of a few hundred atoms.

42
Q
  1. Describe a nanoparticle.
A
  • Nanoparticles, are smaller than fine particles, which have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m).
  • In comparison, coarse particles have diameters between 1 x 10-5 m and 2.5 x 10-6 m. Coarse particles are often referred to as dust.
43
Q
  1. Why do nanoparticles have different properties to the same material that is present as a coarse particle?
A
  • Nanoparticles may have properties different from those for the same materials in bulk because of their high surface area to volume ratio.
  • It may also mean that smaller quantities are needed to be effective than for materials with normal particle sizes.
44
Q
  1. Describe uses for nanoparticles.
A
  • Nanoparticles have many applications in medicine for controlled drug delivery and in synthetic skin.
  • They have uses in electronics; in cosmetics and sun creams; in the development of new catalysts for fuel cells materials; in deodorants and in fabrics to prevent the growth of bacteria.
45
Q
  1. Describe the use of nanoparticles in sun creams.
A
  • Nanoparticles are being used in sun creams. Some of the benefits of nanoparticles in sun creams include better skin coverage and more effective protection from the sun’s ultraviolet rays.
  • Disadvantages include potential cell damage in the body and harmful effects on the environment.