C3. Structure And Bonding (Y10 - Autumn 2)

Question 2

🟢 What is Covalent Bonding, Do They occur in Metals or Non Metals, Do They conduct in Solids + Liquids?

Answer 2

What is Covalent Bonding?
Electrostatic attraction between a shared pair of electrons and the nuclei of the two atoms.

Do They occur in Metals or Non Metals?
Occurs in non-metal elements and compounds.

Do They conduct in Solids + Liquids?
Soilds: Poor Conductors of Electricty and Heat
Liquids: Poor Conductors of Electricity and Heat

Question 3

🟢 What is Metallic Bonding, Do They occur in Metals or Non Metals, and Do They conduct in Solids + Liquids?

Answer 3

What is Metallic Bonding?
The electrostatic force of attraction between the delocalised outer shell electrons and the positive metal ions.

Do They occur in Metals or Non Metals?
Occurs in metal elements and metal alloys.

Do They conduct in Solids + Liquids?
Soilds: Good Conductors of Electricty and Heat
Liquids: Good Conductors of Electricity and Heat

Question 3

🟢 What is Ionic Bonding, Do They occur in Metals or Non Metals, Do They conduct in Solids + Liquids?

Answer 3

What is Ionic Bonding?
Electrostatic attraction between oppositly charged ions.

Do They occur in Metals or Non Metals?
Occurs in compunds containing metals and non-metals.

Do They conduct in Solids + Liquids?
Soilds: Poor Conductors of Electricty and Heat
Liquids: Good Conductors of Electricity and Heat

Question 4

🟢 What are the Properties of Giant Chemical Structures

Answer 4

Examples are: Metallic, Ionic and Covalent.

They are all solids ar room temperture (25°C) with high melting points because lots of energy is required to break many strong bonds.

Question 5

🟢 What are the Properties of Simple Molecular and Monatomic

Answer 5

‘Soft’ solids, liquids or gases at room temperture (25°C) with low melting points and boiling points as not much energy is required to break weak intermolecular forces between molecules

Question 6

🟢 What is an Ion?

Answer 6

An ion is a charged atom of group of atoms formed by the loss or gain of electrons.

The loss or gain of electrons takes place to obtain a full outer shell of electrons. The electronic structure of ions of elements in Groups 1,2, 6 and 7 will be the same as that of a noble gas.

Question 7

🟢 What are Positive and Negative Ions called?

Answer 7

Negative ions are called Anions and form when atoms gain electrons, meaning they have more electrons that protons.

Positive ions are called Cations and form when atoms lose elelctrons, meaning they have more protons than electrons.

Question 8

🟢 What are Dot and Cross Diagrams and the 2d ‘stick’ representation?

Answer 8

Dot-And-Cross:
A dot and cross diagram can model the bonding in a simple molecule : the outer shell of each atom is drawn as a circle. circles overlap where there is a covalent bond. electrons from one atom are drawn as dots, and electrons from another atom as crosses.

2d ‘Stick’ Representation:
This can be a model how many of which particle have what bonds between them, and these bonds are shown by the ‘sticks’.

(Do Practice Questions on these, especially Dot-And-Cross Diagrams and how they should be presented)

Question 9

🟢 What is a Molecule?

Answer 9

A molecule is a substance made up of atoms joined by Covalent Bonds.

Molecules may be elements or compounds and can have simple or giant structures.

Question 10

🟢 Advantages and Disadvantages of a Dot-And-Cross Diagram

Answer 10

Advantages:

• Useful for Illustrating the transfer of electrons
• Indicates from which atoms the ‘bonding’ electrons come from

Disadvantages:

• It fails to illustrate 3D arrangements of the atoms and electron shells
• Doesn’t indicate the relative sizes of atoms and sub-atomic particles

Question 11

🟢 Advantages and Disadvantages of the 2d Stick Representation

Answer 11

Advantages:

• Useful for illustrating the arrangement of atoms in 3D space
• Very useful for visualising the shape of a molecule

Disadvantages:

• Fails at indicating the movement of electrons
• The atoms are placed far apart from each other, which in reality is not correct.

Question 12

🟢 What makes something a Simple Molecular Structure?

Answer 12

Substances that could have a simple molecular structure, because they are poor conductors of electricity due to the fact that they have no charged particles that can move around. The second reason for this is that their melting and boiling points are very low, which is because there are very weak forces of attraction between each of the particles, allowing them to be easily separated.

Question 13

🟢 What Structures are Giant Covalent?

Answer 13

Diamond (C), Graphite (C), Graphene (C), Buckminsterfullerene (C60), Silicon Dioxide - Sand (SiO2)

Question 14

🟢 Simple Molecular Properties and Explanations

Melting Point, Conductivity and Strength

Answer 14

Melting and Boiling Points: Low
Because there are very weak intermolecular forces between the molecules to break, meaning not much energy needs to be used in order to break them apart.

Electrical Conductivity: Does not Conduct
There are no charged particles that are free to move around, meaning that Simple Molecular structures do not have any electrical conductivity.

Strength: Brittle
They are brittle because there are weak intermolecular forces between each molecule, which can be easily pulled apart

Question 15

🟢 Giant Covalent Properties and Explanations (For Silicon Dioxide, Diamond, and Carbon Diamond)
(Melting Point, Conductivity and Strength)

Answer 15

Melting and Boiling Points: Very High
The melting and boiling points will be high because there are lots of strong intermolecular forces to break, which will as a result, will require a lot more energy.

Electrical Conductivity: Does not Conduct
These do not conduct, as there are no charged particles that are not able to move and be mobile, as there aren’t any, meaning it cannot react.

Strength: Very Strong
These structures will be very strong, due to the fact that there are many strong intermolecular forces in a ridged arrangement.

Question 16

🟢 Giant Covalent Properties and Explanations (For Carbon Graphite)
(Melting Point, Conductivity and Strength)

Answer 16

Melting and Boiling Points: Very High
Because you need to break lots of strong covalent bonds, which have very strong intermolecular forces, meaning more energy needs to be used.

Electrical Conductivity: Good Conductor
Because some electrons are delocalised, meaning they are free to move around the structure, meaning charged particles can freely move around all the time, making it a good conductor.

Strength: Brittle
Weak forces between layers so layers can slide off, making it quite brittle overall inbetween these layers, but still has these strong covalent ones inside each layer.

Question 17

🟢 How to Write the Formula of Ionic Compounds?

Answer 17

Find the charges of both parts of the compounds, and then inverse and swap them around. For example:

Potassium Sulphide: K+ and S2- makes K2S

Calcium Hydroxide: Ca2+ and (OH)- makes Ca(OH)2

Iron (iii) Fluoride: Fe3+ and F- makes FeF3

• Carbonate always don’t seem to swap and stays as CO3
• Nitrate is (NO3)
• Hydroxide is (OH)-

Question 18

🟢 Formulas for Ammonia, Ammonium and Methane

Answer 18

Ammonia: NH3
Ammonium: NH4+
Methane: CH4

Question 19

🟢 Diamond’s:

• Structure Type
• Formula
• No. Of Covalent Bonds Per Carbon Atom
• Melting/Boiling Points
• Reason for Melting/Boiling Points
• Electrical Conductivity
• Reason for Electrical Conductivity
• Strength

Answer 19

Structure Type: Giant Covalent

Formula: C

No. Of Covalent Bonds Per Carbon Atom: 4

Melting/Boiling Points: Very High

Reason for Melting/Boiling Points: Need to break strong covelant bonds

Electrical Conductivity: Insulator

Reason for Electrical Conductivity: Has no free electrons or or ions

Strength: Very Hard and Strong

Question 20

🟢 Graphite’s:

• Structure Type
• Formula
• No. Of Covalent Bonds Per Carbon Atom
• Melting/Boiling Points
• Reason for Melting/Boiling Points
• Electrical Conductivity
• Reason for Electrical Conductivity
• Strength

Answer 20

Structure Type: Giant Covalent

Formula: C

No. Of Covalent Bonds Per Carbon Atom: 3 (one delocalised electron per carbon atom + weak forces between layers)

Melting/Boiling Points: Very High

Reason for Melting/Boiling Points: Need to break strong covelant bonds

Electrical Conductivity: Conductor

Reason for Electrical Conductivity: Has 1 delcocalised electron per atom that can carry charge through the whole structure

Strength: Very Strong

Question 21

🟢 Buckminsterfullerene’s:

• Structure Type
• Formula
• No. Of Covalent Bonds Per Carbon Atom
• Melting/Boiling Points
• Reason for Melting/Boiling Points
• Electrical Conductivity
• Reason for Electrical Conductivity
• Strength

Answer 21

Structure Type: Simple Molecular

Formula: C60

No. Of Covalent Bonds Per Carbon Atom: 3 Strong Bonds

Melting/Boiling Points: Not so high

Reason for Melting/Boiling Points: Need to overcome relativly weak forces between molecules (no covelent bonds broken)

Electrical Conductivity: Insulator

Reason for Electrical Conductivity: Has 1 delcocalised electron per atom but they cannot move from one molecule to another

Strength: Soft and Brittle

Question 22

🟢 Graphene’s:

• Structure Type
• Formula
• No. Of Covalent Bonds Per Carbon Atom
• Melting/Boiling Points
• Reason for Melting/Boiling Points
• Electrical Conductivity
• Reason for Electrical Conductivity
• Strength

Answer 22

Structure Type: Giant Covalent

Formula: C

No. Of Covalent Bonds Per Carbon Atom: 3 (one delocalised electron)

Melting/Boiling Points: Very High

Reason for Melting/Boiling Points: Need to break strong covelant bonds

Electrical Conductivity: Conductor

Reason for Electrical Conductivity: Has delcocalised elctrons thay can carry charge through structure

Strength: Soft and Brittle

Question 23

🟢 Why is Graphite used for Pencils

Answer 23

It is used because it is a different colour to paper, as well as the fact that the different layers can slide off onto the paper, therefore marking the paper.

Also, it can be used as a lubricant, as the outer layers easily slide off/away.

Question 24

🟢 How will the properties of nanotubes compare to buckminsterfullerene?

Answer 24

The nanotubes are relativly similar to the buckminsterfullerene in terms of what they are made up of, but the way their structures are shaped are very different because the nanotubes, as the nanotubes are longer in length than in diameter, while holding a cylindrical shape, while the buckminsterfullerene is made up of a spherical shape.

Question 25

🟢 How can nanotubes be used to deliver anti-cancer drugs directly to the site of the tumour, for example?

Answer 25

This can be done by the anti-cancer drugs being put inside of the nanotubes, and then fired at the tumour, allowing the specific site of where the caner is to be targeted, and not the surroundung healthy cells aroud it.

Question 26

❌ *What is so special about Nano Particles and the Surface area to Volume Ratio?

Answer 26

One of the most interesting features of nanoparticles is their very high surface area to volume ratio.

Question 27

🟢 The Equations of Surface Area to Volume ratio

Answer 27

Surface Area /Volume = Surface Area To Volume Ratio

Surface Area /Surface Area To Volume Ratio = Volume

Surface Area To Volume Ratio x Volume = Surface Area

Question 28

🟢 How to Calculate Surface Area and Volume

Answer 28

Surface Area:
You get the width and the height and work out each face of the shape using this principle. Then, you add each individul face’s surface area to get the shape’s overall surface area.

Volume:
You get the width, the height and the depth and times these three things altogether.

Question 29

❌ *The Main Uses and Applications of Nanoparticles and/or Fullerenes

Answer 29

• The main industrial application of nanoparticles is in catalysis due to their high surface area to volume ratios
• Titanium dioxide in nanoparticle form is used in suncreens as it blocks UV light but leaves no white marks on the skin while also peoviding better coverage than other suncreams.
• Fullerenes are used in medicine and drug design as they are more easily absorbed than other particles and can deliver drugs to target areas more effectively.
• Fullerenes are also used in electronic circuitry and as coatings for artificial limbs and joints.
• Nanoparticles of silver are sprayed onto the fibres of medical clothing and surgical masks which gives them the flexibility of a material but with the added benefit of the antibacterial properties of silver metal.

Question 30

❌ *The Risks of Using Nanoparticles

Answer 30

• The use of nanoparticles in science is in it’s early stages so there are still a lot of unknown factors and potential risks.
• In particular there is a lack of understanding on how they may affect helth particularly in the long term.
• Even a small amount of toxicity in a particular nanoparticle would be multiplied due to the high surface area to volume ratio.
• This coupled with the fact that they are not easily disposed of by the body are a cause for caution in the medical application of nanoparticles.

Question 31

🟢 What are the Structure of Metallic Bonds

Answer 31

In metallic structures the outer shell electrons are delocalised leaving a lattice (regular pattern) of positive ions.

Question 32

🟢 Explain which group of metal elements will have the strongest metallic bond?

Answer 32

The group of metal that will have the strongest metallic will be group 3, because they will have the largest amount of delocalised electrons for the positive ions to be able to bond with, therefore, meaning more bonds and a stronger attraction.

Question 33

🟢 Metallic Properties and Explanations

Melting Point, Conductivity, Strength and Malleability

Answer 33

Melting and Boiling Points: High
Because it is a giant structure, as there are many strong bonds (metallic bonds) inbetween the molecules, resulting in more energy being neccessary to break it down.

Electrical and Thermal Conductivity: Good Conductor
The electrical conductivity and thermal will be good, as there are charged delocalised electrons that are able to move around the whole structure and therefore conduct.

Strength: Strong
The strength of metals are good because there are strong intermolecular metallic bonds between each sub-molecular particles in a strong lattice structure.

Malleability: Good
The malleablility of metals are good because you are able to shift each layer of positive electrons, as there will still be the negative outer shell electrons, meaning the particles will not repel, because the structure will not be changed, just moved, unlike an ionic compound.

Question 34

🟢 Ionic Properties and Explanations

Melting Point, Conductivity and Strength

Answer 34

Melting and Boiling Points: High
Because it is a giant structure, as there are many strong bonds (ionic bonds) inbetween the molecules, resulting in more energy being neccessary to break it down.

Electrical and Thermal Conductivity: Good Conductor in Liquid, not Solid
The electrical conductivity and thermal conductivity will be good when it is a liquid, as now there are charged ions that are able to move around the whole structure and therefore conduct, whereas a solid, these charged particles are not able to move freely, as they stay in fixed positions.

Strength: Strong
The strength of metals are good because there are strong intermolecular ionic bonds between each sub-molecular particles in a strong lattice structure.

Question 35

🟠 What is an Alloy?

Answer 35

An alloy is a mixture of an element that contains at least one metal. It can be bonded with either another metal or a non-metal. They also contain atoms of different sizes to make this slightly distorted the regular arrangement/structure.

Question 36

🟠 Why are Alloys more useful than Pure Metals

Answer 36

Alloys are more useful than pure metals because you are able to add certain properties to them by combining a metal with another element, meaning they can share properties. This allows alloys to either have higher melting and boiling points, resistant to corrosion, higher malleablility and so on e.c.t.

Question 37

🟢 Monotomic:

• Melting and Boiling Points
• Conductivity as a Solid
• Conductivity when melted
• Solubility in Water
• Conductivity of Solution

Answer 37

Melting and Boiling Points: Low

Conductivity as a Solid: Does not conduct

Conductivity when melted: Does not conduct

Solubility in Water: Insoluble

Conductivity of Solution: Insoluble

Question 38

🟢 Conductivity of Ionic, Simple Molecular, Giant Covalent and Metallic Solutions

Answer 38

Ionic: Conducts
Simple Molecular: Insoluble (usually)
Giant Covalent: Insoluble
Metallic: Insoluble

Question 39

🟢 What is a Polymer?

Answer 39

A substance made from very large molecules made up of many repeating units.

Question 40

🟢 What is a Fullerene?

Answer 40

Formed of the element carbon that can exist as large cage-like structures, based on hexagonal rings of carbon atoms.

Question 41

🟢 What are Coarse Particles?

Answer 41

Coarse particles are the relatively large airborne particles mainly produced by the mechanical break-up of even larger solid particles. Examples of coarse particles include dust, pollen, spores, fly ash, and plant and insect parts.

Question 42

🟢 What are Fine Particles?

Answer 42

Fine particles are airborne particles which are smaller than coarse particles. They have an aerodynamic diameter of 2.5 µm or less (PM2.5). The fine particles which are smaller than 0.1 µm are referred to as nanoparticles (PM 0.1).

Question 43

❌ *What are Nano Particles?

Answer 43

A nanoparticle (or ultrafine particle) is usually defined as a particle of matter that is between 1 and 100 nanometres in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions.

Question 44

🟢 Why do Metals have high melting and boiling points

Answer 44

Giant lattice structure of many strong bonds require lots of heat energy to break.

Question 45

🟢 Why are metals malleable and ductile

Answer 45

Metals are malleable and ductile, because the layers of positive metal ions can easily slide over each other, while not breaking the lattice too much, which makes them malleable.

(Layers of metal ions can slide over each other without repelling.)

Question 46

🟢 Why are metals good conductors of thermal and electrical energy

Answer 46

Metals are good conductors of thermal and electrical energy because there are many delocalised electrons that have the freedom to be able to vibrate and move in the structure.

(Delocalised (outer shell) electrons allow charge or heat to flow through the structure.)

Question 47

🟢 How is Buckminsterfullerene a good lubricant?

Answer 47

They are a great lubricant due to their spherical shape, which allows one molecule to roll/slide over the other, which is what makes it such a good lubricant

Question 48

🟢 Aluminium metal is extracted from aluminium oxide by electrolysis. The aluminium oxide must be molten to conduct and melts at 2072°C. Explain, by discussing structure and bonding, why aluminium oxide must
be molten to conduct and why it has a high melting point?

Answer 48

Aluminium oxide is an ionic, meaning it will be held together in a giant ionic lattice structure with many electrostatic forces of attraction between oppositely charged ions in all directions holding the structure together when it’s a solid. This means that this substance will have a very high melting point (2072°C), as lots of energy (i.e heat) is needed to break these many strong ionic bonds that hold the ions together. Because of the structure, it also means that no free ions or delocalised electrons are free to carry charge around the structure. However, if the substace is melted, it will be able to conduct electricty, as there are now free ions and delocalised electrons that are able to carry electrical charges around the structure, allowing the substance to conduct.

Question 49

🟢 What Structure do Ionic Compounds come in What makes the Structure so Strong

Answer 49

1. Ionic compounds have a structure called a giant ionic lattice.
2. The ions form a closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions, in all directions in the lattice.