topic 2 - bonding, structure, and properties of matter Flashcards
1
Q
What are nanoparticles and what is their size range?
A
Nanoparticles are particles that are 1-100 nanometers (nm) across containing a few hundred atoms.
2
Q
How do nanoparticles compare in size to fine and coarse particles?
A
Nanoparticles are smaller than fine particles (PM2.5) which have diameters between 100 and 2500 nm (1 x 10^-7 m to 2.5 x 10^-6 m). Coarse particles (PM10) have diameters between 1 x 10^-5 m and 2.5 x 10^-6 m.
3
Q
What happens to the surface area to volume ratio as the size of a cube decreases?
A
As the side of a cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.
4
Q
What is the significance of the surface area to volume ratio in nanoparticles?
A
Nanoparticles have a high surface area to volume ratio resulting in different properties compared to the bulk chemical they are made from often requiring smaller quantities to be effective.
5
Q
What are fullerenes in the context of nanoparticles?
A
Fullerenes are a type of nanoparticle that consist of carbon atoms arranged in a hollow sphere ellipsoid or tube and they exhibit unique properties compared to larger carbon structures.
6
Q
Why do nanoparticles have different properties than their bulk counterparts?
A
Nanoparticles have a different structure at the atomic level due to their size resulting in unique chemical and physical properties that differ from the bulk material.
7
Q
What is the typical size of coarse particles (PM10) in comparison to nanoparticles?
A
Coarse particles (PM10) typically have diameters between 1 x 10^-5 m and 2.5 x 10^-6 m making them significantly larger than nanoparticles which are 1-100 nm.
8
Q
Explain the term “bulk chemical” as it relates to nanoparticles.
A
Bulk chemicals refer to the larger quantities of a substance typically composed of many particles whose properties may differ significantly from the properties of nanoparticles of the same substance due to size and surface area.
9
Q
What unique advantages do nanoparticles offer in chemical applications?
A
The unique advantages of nanoparticles include their increased reactivity and effectiveness in smaller quantities due to their high surface area to volume ratio which can lead to innovations in areas like drug delivery catalysis and materials science.
10
Q
Enumerate the size distinctions between nanoparticles fine particles and coarse particles with their respective diameters.
A
- Nanoparticles: 1-100 nm
11
Q
- Fine particles (PM2.5): 100-2500 nm (1 x 10^-7 m to 2.5 x 10^-6 m)
A
12
Q
- Coarse particles (PM10): 1 x 10^-5 m to 2.5 x 10^-6 m.
A
13
Q
What are carbon nanotubes and their key properties?
A
Carbon nanotubes are cylindrical structures composed of carbon atoms arranged in a hexagonal lattice. They have a high surface area to volume ratio extraordinary strength electrical conductivity and thermal conductivity.
14
Q
List the uses of carbon nanotubes.
A
- Catalysts due to their high surface area. 2. Selective sensors for detecting specific molecules. 3. Stronger lighter building materials. 4. Cosmetics such as suntan cream and deodorant (leave no white marks). 5. Lubricant coatings to reduce friction suitable for artificial joints and gears. 6. Conductors for small electrical circuits in computers.
15
Q
What are the possible disadvantages of carbon nanotubes?
A
Concerns include potential toxicity to humans with the possibility that nanoparticles can enter the brain from the bloodstream and cause harm.
16
Q
Define compounds in the context of chemistry.
A
Compounds are substances formed when two or more elements are chemically combined in a fixed ratio resulting in unique properties distinct from the individual elements.
17
Q
What are the three types of strong chemical bonds?
A
The three types of strong chemical bonds are: 1. Ionic bonds 2. Covalent bonds 3. Metallic bonds.
18
Q
Describe ionic bonds.
A
Ionic bonds are formed when electrons are transferred from one atom to another resulting in the formation of oppositely charged ions that attract each other.
19
Q
What distinguishes covalent bonds from ionic bonds?
A
Covalent bonds involve the sharing of electrons between atoms whereas ionic bonds involve the transfer of electrons and the resultant electrostatic attraction between charged ions.
20
Q
Explain metallic bonds.
A
Metallic bonds are formed between metal atoms characterized by a ‘sea of delocalized electrons’ that allows for conductivity malleability and ductility.
21
Q
What role do carbon nanotubes play in electronics?
A
Carbon nanotubes can be used in small electrical circuits for computers due to their excellent electrical conductivity contributing to the miniaturization and efficiency of electronic devices.
22
Q
How do carbon nanotubes enhance the properties of materials in construction?
A
Carbon nanotubes improve the strength-to-weight ratio of building materials making them lighter and stronger which is beneficial for structural integrity and energy efficiency.
23
Q
What are some examples of cosmetic applications for carbon nanotubes?
A
Examples of cosmetic applications include suntan cream and deodorants where the nanotubes help produce products that do not leave white marks on the skin.
24
Q
What is an ion?
A
An ion is an atom that has lost or gained electrons resulting in a net electric charge.
25
What occurs in compounds formed from metals combined with non-metals?
Charged ions occur in compounds formed from metals combined with non-metals leading to ionic bonding.
26
What is ionic bonding?
Ionic bonding is the electrostatic attraction between positively and negatively charged ions formed when electrons are transferred from one atom to another.
27
What happens to metal atoms during ionic bonding?
Metal atoms lose electrons to become positively charged ions.
28
What happens to non-metal atoms during ionic bonding?
Non-metal atoms gain electrons to become negatively charged ions.
29
What is the significance of groups 1 and 2 in metal ions?
Metals in Groups 1 and 2 lose electrons to form positive ions leading to the formation of ionic compounds.
30
What is the significance of groups 6 and 7 in non-metal ions?
Non-metals in Groups 6 and 7 gain electrons to form negative ions which are essential for ionic compound formation.
31
What does gaining a full outer shell of electrons mean for an ion?
Gaining a full outer shell of electrons allows ions to achieve a stable electronic structure similar to that of a noble gas (Group 0 element).
32
What is covalent bonding?
Covalent bonding occurs when particles (atoms) share pairs of electrons typically seen in most non-metallic elements and the compounds of non-metals.
33
What is metallic bonding?
Metallic bonding involves particles (atoms) sharing delocalized electrons characteristic of metallic elements and alloys.
34
Explain the electron transfer in ionic bonding using a dot-and-cross diagram.
In a dot-and-cross diagram for ionic bonding dots represent the valence electrons of one atom (usually a non-metal) while crosses represent the valence electrons of another atom (usually a metal). This diagram visually demonstrates how electrons are transferred between the atoms during the formation of an ionic compound such as NaCl.
35
Provide an example of an ionic compound formation.
In the formation of sodium chloride (NaCl) sodium (a metal from Group 1) loses one electron to become Na⁺ while chlorine (a non-metal from Group 7) gains that electron to become Cl⁻. The resulting Na⁺ and Cl⁻ ions attract each other to form the ionic compound NaCl.
36
What defines ionic compounds and how are they structured?
Ionic compounds are defined as a giant structure of ions held together by strong electrostatic forces of attraction between oppositely charged ions. Their structure is three-dimensional and the electrostatic forces act in every direction throughout the lattice.
37
Give an example of an ionic compound and describe its ions.
An example of an ionic compound is sodium chloride (NaCl). In this compound sodium ions (Na+) are small blue particles while chloride ions (Cl-) are larger green particles.
38
What is covalent bonding and how does it work?
Covalent bonding is a type of chemical bond where atoms share one or more pairs of electrons to achieve stability. This type of bond is prevalent in small molecules such as HCl H2 O2 Cl2 NH3 and CH4 which have strong covalent bonds within their molecular structures.
39
What are polymers and how are they related to covalent bonding?
Polymers are large molecules composed of many repeating units that are covalently bonded together. Their structure allows for significant size and complexity due to the formation of extensive chains of atoms.
40
What are giant covalent structures and provide examples.
Giant covalent structures are macromolecules consisting of many atoms covalently bonded in a lattice. Examples of giant covalent structures include diamond and silicon dioxide (SiO2).
41
Describe the different types of diagrams that can be used to represent covalent and ionic compounds.
Various types of diagrams can be used to illustrate covalent and ionic compounds including: 1. Dot and cross diagrams which show the arrangement of electrons; 2. Repeat unit representations for polymers using a single line to depict a covalent bond; 3. Ball and stick models which represent atoms as balls and bonds as sticks; 4. Two- and three-dimensional structural diagrams.
42
What is metallic bonding and how is it characterized?
Metallic bonding occurs in metals and involves positive ions (metal atoms that have lost electrons) surrounded by a 'sea' of delocalized electrons. This electron delocalization allows metal atoms to conduct electricity and contributes to the malleability and ductility of metals.
43
How does ionic compound structure affect their properties particularly melting and boiling points?
Ionic compounds have very high melting and boiling points due to the strong electrostatic forces of attraction between the oppositely charged ions. These forces require significant energy to overcome when changing the state of the compound.
44
What is the significance of the lattice structure in ionic compounds?
The lattice structure in ionic compounds is significant because it maximizes the attractive forces between oppositely charged ions while minimizing repulsion between ions of the same charge creating a stable formation.
45
What makes covalent bonds strong compared to other types of bonds?
Covalent bonds are considered strong because they involve the sharing of electron pairs between atoms resulting in a stable electron configuration for both atoms involved. This sharing creates a strong attraction that holds the atoms together.
46
Explain the concept of delocalization in metallic bonding.
Delocalization in metallic bonding refers to the presence of electrons that are not associated with a single atom but are free to move throughout the metal lattice. This delocalization contributes to various properties of metals such as electrical conductivity and thermal conductivity.
47
What is the role of repeat units in the structure of polymers?
Repeat units in the structure of polymers are the smaller identical or similar units that make up the larger polymer chain. They show how the polymer is constructed from simple monomer units through covalent bonding.
48
Differentiate between small covalent molecules and giant covalent structures in terms of size and bonding.
Small covalent molecules consist of a limited number of atoms bonded together (e.g. H2 O2) while giant covalent structures are made up of a vast array of atoms in a continuous lattice bonded covalently (e.g. diamond). The bonding in small molecules is localized while in giant structures bonding extends throughout the entire structure.
49
What are delocalised electrons and where are they found?
Delocalised electrons are electrons that have been lost from their respective atoms to form positive ions allowing them to move freely through the metallic structure. They create a system of shared electrons throughout the metal contributing to the strength of metallic bonds.
50
How do metallic bonds contribute to the properties of metals?
Metallic bonds formed by delocalised electrons that are free to move throughout the metallic structure contribute to the strength electrical conductivity malleability and ductility of metals.
51
What are the three states of matter?
The three states of matter are solid liquid and gas.
52
What processes occur at the melting point?
At the melting point a solid changes into a liquid which is known as melting and the reverse process is called freezing.
53
What processes occur at the boiling point?
At the boiling point a liquid changes into a gas which is known as boiling and the reverse process is called condensing.
54
How does particle theory relate to states of matter?
Particle theory describes how the arrangement and movement of particles in a substance determine its state of matter. Solids have closely packed particles that vibrate in place liquids have more spaced out particles that can move around each other and gases have widely spaced particles that can move freely.
55
What is the energy requirement when changing states from solid to liquid?
The amount of energy needed to change state from solid to liquid is known as the latent heat of fusion. This energy is required to overcome the forces holding the solid particles together.
56
What is the significance of delocalised electrons in metallic bonding?
Delocalised electrons play a critical role in metallic bonding by allowing electrons to move freely throughout the lattice structure of the metal creating a 'sea of electrons' which accounts for many metallic properties such as strength conductivity and malleability.
57
Explain melting and freezing in terms of energy change.
During melting energy is absorbed to overcome intermolecular forces and allow particles to move freely which transforms a solid into a liquid. In freezing energy is released as particles lose energy becoming more ordered and transitioning from a liquid to a solid state.
58
What role does temperature play in state changes?
Temperature is a measure of the average kinetic energy of particles in a substance. A change in temperature can add or remove energy facilitating the changes of state: solids melt to liquids and liquids boil to gases with an increase in temperature while the reverse happens with a decrease in temperature.
59
What factors determine the state of matter (liquid or gas) of a substance?
The state of matter depends on the strength of the forces between the particles of the substance. Stronger forces result in higher melting and boiling points.
60
What role do particle nature and structure play in determining state changes?
The nature of the particles involved which depends on the type of bonding and the structure of the substance plays a crucial role in determining how a substance changes from one state to another.
61
What is the relationship between the strength of interparticle forces and melting/boiling points?
The stronger the forces between the particles the higher the melting point and boiling point of the substance.
62
What limitations exist in the simple model of particles in matter?
Limitations of the simple model include: 1) It does not include forces acting between particles. 2) All particles are represented as solid spheres. 3) The spheres are depicted as solid and not reflecting the nature of actual particles.
63
What are the state symbols used in chemical equations for different states of matter?
The state symbols are: solid = 's' liquid = 'l' gas = 'g' and aqueous solution = 'aq'.
64
Describe the structure of ionic compounds.
Ionic compounds have regular structures known as giant ionic lattices characterized by strong electrostatic forces of attraction in all directions between oppositely charged ions.
65
Why do ionic compounds have high melting and boiling points?
Ionic compounds have high melting and boiling points because a significant amount of energy is needed to break the many strong ionic bonds present in their lattice structure.
66
What happens to ionic compounds when they are melted or dissolved in water?
When melted or dissolved in water ionic compounds conduct electricity due to the mobility of the ions within the liquid or solution.
67
What type of forces exist in ionic compounds?
Ionic compounds are held together by strong electrostatic forces of attraction between positively and negatively charged ions.
68
What can be inferred about the conductivity of a solid ionic compound?
Solid ionic compounds do not conduct electricity because their ions are fixed in place within the lattice structure and cannot move freely.
69
Why can ionic compounds conduct electricity when dissolved in a liquid state but not as solids?
Ionic compounds can conduct electricity in a liquid state because the ions are free to move and carry current. In contrast when they are in solid form the ions are fixed in place within a lattice structure preventing them from moving and thus conducting electricity.
70
What are the typical physical states and boiling/melting points of substances that consist of small molecules?
Substances that consist of small molecules are usually in gaseous or liquid states and have low boiling and melting points due to weak intermolecular forces between the molecules.
71
What happens to the intermolecular forces when small molecules boil or melt?
When small molecules boil or melt the weak intermolecular forces between the molecules are broken. However the covalent bonds within the molecules themselves remain intact.
72
How does the size of small molecules affect their boiling and melting points?
The boiling and melting points of small molecules increase with the size of the molecules because larger molecules have stronger intermolecular forces.
73
Do small molecules conduct electricity? Why or why not?
Small molecules do not conduct electricity because they do not have an overall electric charge and thus lack free-moving charged particles.
74
What are the characteristics of polymers in comparison to small molecules?
Polymers consist of very large molecules where atoms are linked by strong covalent bonds. They have relatively strong intermolecular forces between the polymer molecules resulting in these substances being solids at room temperature.
75
What defines a giant covalent structure?
Giant covalent structures consist of a large number of atoms linked together by covalent bonds in a continuous network resulting in strong bonding that gives the material high melting and boiling points.
76
What type of forces are present between small molecules and how do they affect their properties?
Small molecules experience weak intermolecular forces which result in low melting and boiling points and the inability to conduct electricity.
77
What are covalent bonds and how do they differ from intermolecular forces?
Covalent bonds are strong links formed between atoms in a molecule by the sharing of electron pairs while intermolecular forces are weaker forces that occur between individual molecules.
78
Why are polymers solid at room temperature?
Polymers are solid at room temperature due to the relatively strong intermolecular forces between the polymer molecules which prevents them from flowing like liquids.
79
How does the structure of giant covalent substances contribute to their physical properties?
The structure of giant covalent substances which features a vast network of covalent bonds contributes to their high melting and boiling points because breaking these bonds requires a significant amount of energy.
80
What are some examples of giant covalent structures?
Examples of giant covalent structures include diamond graphite and silicon dioxide (quartz).
81
What are structures with very high melting points made of?
Structures with very high melting points are made of solids where all atoms are linked by strong covalent bonds.
82
What is required to melt or boil substances with strong covalent bonds?
To melt or boil substances with strong covalent bonds these bonds must be overcome.
83
Give examples of substances with strong covalent bonds. What elements are they forms of?
Examples of substances with strong covalent bonds include diamond and graphite both forms of carbon and silicon dioxide (silica).
84
What kind of atomic structure do metals have?
Metals have giant structures of atoms that are held together by strong metallic bonding.
85
What are the melting and boiling point characteristics of most metals?
Most metals have high melting and boiling points.
86
What is a distinct property of metal layers regarding their structure?
The layers of atoms in metals can slide over each other allowing metals to be bent and shaped.
87
What are alloys?
Alloys are made from two or more different types of metals.
88
How do different sized atoms in alloys affect their properties compared to pure metals?
Different sized atoms in alloys distort the layers in the structure making it harder for them to slide over each other resulting in alloys being harder than pure metals.
89
Why are metals good conductors of electricity?
Metals are good conductors of electricity because delocalised electrons carry electrical charge through the metal.
90
What makes metals good conductors of thermal energy?
Metals are good conductors of thermal energy because energy is transferred easily through the structure facilitated by the free movement of delocalised electrons.
91
What are the roles of delocalised electrons in metals?
Delocalised electrons allow metals to conduct electricity and thermal energy efficiently.
92
What is the structure of diamond?
In diamond each carbon atom is covalently bonded to four other carbon atoms creating a strong and rigid three-dimensional structure. This arrangement leads to diamond's characteristic hardness.
93
What are the properties of diamond?
Diamond is very hard has a very high melting point and does not conduct electricity due to the absence of free-moving electrons.
94
Describe the structure of graphite.
In graphite each carbon atom is covalently bonded to three other carbon atoms forming layers of hexagonal rings. There are no covalent bonds between the layers allowing them to slide over one another.
95
What allows graphite to be soft and slippery?
Graphite's softness and slipperiness result from the weak intermolecular forces between the layers which means they can slide past each other easily.
96
What is meant by delocalised electrons in graphite?
In graphite one electron from each carbon atom becomes delocalised meaning it is free to move across the structure similar to how electrons behave in metals.
97
Why can graphite conduct electricity?
Graphite can conduct electricity because the delocalised electrons are free to move allowing for the flow of electric current.
98
What is graphene?
Graphene is a single layer of graphite consisting of a two-dimensional arrangement of carbon atoms in a hexagonal lattice.
99
What are fullerenes?
Fullerenes are molecular forms of carbon arranged in hollow structures which can include shapes such as spheres ellipsoids or tubes.
100
Compare the conductivity of diamond and graphite.
Diamond is an insulator and does not conduct electricity due to the lack of delocalised electrons whereas graphite conducts electricity due to the presence of delocalised electrons.
101
What is the significance of delocalised electrons in materials science?
Delocalised electrons play a crucial role in the electrical conductivity of materials determining whether a substance behaves as an insulator conductor or semiconductor.
102
What determines the high melting point of diamond?
The high melting point of diamond is due to the strong covalent bonds between carbon atoms throughout its three-dimensional lattice structure requiring a significant amount of energy to break.
103
Explain the term 'intermolecular forces' as it relates to graphite.
Intermolecular forces refer to the weak forces of attraction between the layers of graphene in graphite allowing these layers to slide over each other and contributing to the material's softness.
104
What are the primary properties of graphene that make it useful in electronics and composites?
Graphene is very strong due to the tight bonding of atoms within its layers and it is also elastic because the planes of atoms can flex easily without breaking apart.
105
What are fullerenes and what characteristic shapes do they have?
Fullerenes are molecules of carbon atoms that form hollow shapes primarily based on hexagonal rings of carbon atoms. They may also contain five or seven carbon atom rings.
106
What is the first fullerene that was discovered and what is its chemical formula?
The first fullerene discovered is Buckminsterfullerene with the chemical formula C60. It has a spherical shape.
107
Describe carbon nanotubes and their structural characteristics.
Carbon nanotubes are cylindrical fullerenes characterized by a very high length to diameter ratio.
108
What are some applications of carbon nanotubes?
Carbon nanotubes are useful in nanotechnology electronics and materials. They can be used as lubricants drug delivery systems and catalysts. Additionally they can reinforce materials such as tennis rackets.
109
Explain how graphene's elasticity benefits its applications in technology.
Graphene's elasticity allows it to maintain structural integrity while being flexible which is beneficial for applications requiring materials that can bend without breaking particularly in electronics.
110
What types of bonding are present in graphene and how do they contribute to its strength?
Graphene exhibits covalent bonding between carbon atoms which creates a strong planar structure. The sp2 hybridization of carbon atoms provides strong sigma bonds and delocalized pi bonds contributing to its exceptional tensile strength.
111
How are fullerenes typically synthesized?
Fullerenes can be synthesized via methods such as arc discharge laser ablation and chemical vapor deposition which allow controlled formation of carbon structures.
112
Can carbon nanotubes be used in drug delivery? If so how?
Yes carbon nanotubes can be used in drug delivery by encapsulating therapeutic agents within their hollow structures allowing for targeted delivery and controlled release within the body.
113
What is one significant advantage of using carbon nanotubes as reinforcements in materials?
One significant advantage is that carbon nanotubes can significantly increase the strength and toughness of composite materials without adding substantial weight making them ideal for applications in aerospace and sports equipment.
114
What are some other names given to fullerenes based on their structure?
Depending on the arrangement and number of carbon atoms fullerenes may also be referred to as buckyballs (for spherical forms like C60) or carbon nanotubes (cylindrical forms).
115
Discuss the impact of graphene on the development of electronic components.
Graphene's high electrical conductivity and rapid electron mobility open up possibilities for advanced electronic components such as transistors sensors and flexible circuits potentially outperforming traditional materials.
116
What role do carbon atoms play in the structure of fullerenes and carbon nanotubes?
Carbon atoms are the fundamental building blocks of fullerenes and carbon nanotubes forming the necessary structural framework through covalent bonds that define their unique geometric shapes and properties.
117
What is the unique structural feature of carbon nanotubes that provides their exceptional properties?
The unique structural feature of carbon nanotubes is their cylindrical geometry combined with the seamless arrangement of carbon atoms which contributes to high tensile strength electrical conductivity and thermal stability.
118
In terms of reinforcements how do carbon nanotubes affect the mechanical properties of composite materials?
Carbon nanotubes improve the mechanical properties of composite materials by providing enhanced strength stiffness and durability leading to lighter and stronger products.
119
Discuss how the research and application of fullerenes and carbon nanotubes are currently evolving in the field of nanotechnology.
Research on fullerenes and carbon nanotubes is rapidly evolving focusing on self-assembly functionalization and integration into nanoscale devices which can lead to breakthroughs in various fields including medicine electronics and materials science.
